What is Forex?
The Forex Market is a cash market where currencies of different nations are traded. 

The Best Explanation I could find for Forex Trading was from Yahoo, below.

The investor’s goal in Forex trading is to profit from foreign currency movements. Forex trading or currency trading is always done in currency pairs. For example, the exchange rate of EUR/USD on Aug 26th, 2003 was 1.0857. This number is also referred to as a “Forex rate” or just “rate” for short. If the investor had bought 1000 euros on that date, he would have paid 1085.70 U.S. dollars. One year later, the Forex rate was 1.2083, which means that the value of the euro (the numerator of the EUR/USD ratio) increased in relation to the U.S. dollar. The investor could now sell the 1000 euros in order to receive 1208.30 dollars. Therefore, the investor would have USD 122.60 more than what he had started one year earlier. However, to know if the investor made a good investment, one needs to compare this investment option to alternative investments. At the very minimum, the return on investment (ROI) should be compared to the return on a “risk-free” investment. One example of a risk-free investment is long-term U.S. government bonds since there is practically no chance for a default, i.e. the U.S. government going bankrupt or being unable or unwilling to pay its debt obligation.When trading currencies, trade only when you expect the currency you are buying to increase in value relative to the currency you are selling. If the currency you are buying does increase in value, you must sell back the other currency in order to lock in a profit. An open trade (also called an open position) is a trade in which a trader has bought or sold a particular currency pair and has not yet sold or bought back the equivalent amount to close the position.

Site Ideas
There are various topics you can build a Forex site about including…
Basic How To Forex Site
Forex Tool Web Site (There are a ton of Forex tools including a Pivot Points Calculator)
A Forex Forum

Forex is Rising In Popularity 
For this reason it may be hard to create a new site and jump strait into the Topic of Forex, you may want to find a very specific Niche, and work with that.

What Exactly is Forex Paying
These are the Average Cost Per Click Values for Various Forex Related Keywords based on Googles Traffic Estimator
Forex $6.75
Forex Trading $8.69
Forex Market $6.36
Forex Tool $9.48 

What is a Domain Name?
A name that identifies one or more IP addresses. For example, the domain name microsoft.com represents about a dozen IP addresses. Domain names are used in URLs to identify particular Web pages. For example, in the URL http://valuedkeywords.com/index.php, the domain name is valuedkeywords.com. 

Applying the Keyword “Domain Name” to a Web Site.
 There are a couple different types of web sites you can produce using the term “Domain Name”, here are a few examples…
You could Review and Compare Domain Name Registrars. I Domain Name Registrar is a Company that distribute Domain Names, for a price of course. For Example, I bought my Domain Name from the Registrar, GoDaddy.
You could create a Domain Name Seller site. This is where you Buy Valuable Domain Names, and then sell them (a Domain Brokerage) for a higher price, however, this could be risky buisiness. 

What is Online Banking?
The concept of Online Banking is actually pretty simple. Online banking is the practice of making bank transactions or paying bills via the Internet. 

Paths to Go…
If you are considering creating a Web Site based on Online Banking there are many options.
One common Option would be to create a Online Bank Review Site. Compare and Rate the top Online Banking Options. However, this is only one simple option out of a pool of many.

Further Reading…
Anyways, if you are looking for more Information on Online Banking Check out this link…

Online Banking Basics
 

So what exactly is Mesothelioma?

Definition: a malignant tumor of the covering of the lung or the lining of the pleural and abdominal cavities, often associated with exposure to asbestos.

If You are looking for more information on Mesothelioma Search Google.

Sub Categories of Mesothelioma

Mesothelioma Lawyer
Mesothelioma Attorney
Mesothelioma Diagnosis
Mesothelioma Lawsuits
Mesothelioma Symptoms

 Other Notes
Even if you have never heard of Mesothelioma, it is a pretty popular subject. Google’s Keyword Tool says the term “Mesothelioma” recieves about 301,000 searches per month. Anyways, there are many different kinds of sites you can create to dive into the Mesothelioma Niche. Just make sure you learn enough about the disease and start a site, maybe you could even start a forum for those dealing with Mesothelioma.

Definition: Anti-aging addresses how to prevent, slow, or reverse the effects of aging and help people live longer, healthier, happier lives. 

Basics of Anti-Aging
I did some research and found theat Anti-Aging is a huge topic. Anti-Aging is most commonly seen on the internet in the form of cosmetic Anti-Aging Cream Advertisements.  The anti-aging marketplace includes nutrition, physical fitness, skin care, hormone replacements, vitamins, supplements, and herbs. 

However, there are many other aspects of the Keyword, “Anti-Aging”. Anti-aging also includes anti-aging psychology, which include coping skills for resiliently handling change, stress, and aging. Yet Another part of Anti-aging is Life Extension.

Ideas
Since the Anti-aging Topic is so broad the Options are endless, here are some common Ideas…
Anti-Aging Product Review Site – This could also be a Forum, and could be more specific, such as an Anti-Aging Exfoliating Cream Review Site (or Another Product).
Anti-Aging Excersise Web Site - Exercises that help Prolong life Expectancy.

There are endless ideas using “Anti-aging” as the keyword. However, remember, as always, to keep very specific so that Your Site is unique. If you go into a Broad Topic Your Site will just be a fish in the Sea and it will take a lot of extra promotion to get Noticed.
 

So What is a Mortgage?
Most home buyers have to borrow money in order to purchase their home. Few have enough money sitting in the bank, or in other easily saleable assets, to pay the entire cost of the home at once. (Even those few who do have enough money usually find it financially advantageous – perhaps for extra tax relief — to borrow some of the money.) The home loan they receive is called a “mortgage.” Generally, a mortgage is a loan of money to the home owner secured by a “lien” on the real estate. (http://real-estate-law.freeadvice.com/mortgage_matters/mortgage.htm)

Tips
I Found This Article which gives a couple good Tips on how to Produce a nice Mortgage/ Broker Web Site.

Basic Hotel Information
Definition: a commercial establishment offering lodging to travelers and sometimes to permanent residents, and often having restaurants, meeting rooms, stores, etc., that are available to the general public.

There are a ton of subjects related to the Keyword “Hotel”, below are a few Popular well paying Niches…

Specific Hotel Niches
Cheap Hotels
Hotel Rooms 
Beach Hotels 

Ideas
There are many Options for creating Hotel based Web Site, here are a few Example:
Hotel Review Web Site 
Hotel Deal Web Site 

However, the Hotel, as a Keyword, is a very broad topic, so there are many possibilities available. 

Tips
Even the Specified Keywords above are Heavy in Competition, choose an even more specific Niche. You can be creative and mix Keywords to come up with a more specific Niche. Example: Cheap Beach Hotels in Panama Florida Reviews.

Also, take advantage of sites that may help. Looking around I found Hotel Internet Marketting which provides many good tips.

What is Insurance

Definition: the act, system, or business of insuring property, life, one’s person, etc., against loss or harm arising in specified contingencies, as fire, accident, death, disablement, or the like, in consideration of a payment proportionate to the risk involved. 

Types of Insurance (With High PPC Value)
Auto Insurance or Car Insurance
Health Insurance
Home Insurance
Life Insurance 
Travel Insurance 

Notes
Insurance is a very competitive subject on the Internet, and even Sub-Niches such as Auto Insurance, Health Insurance, etc. are terribly competitive. For this reason it would be very hard to build a site around any of these Keywords. However, if you did manage to successfully promote a site on any of the keywords above you could recieve a very fair ammount of money. If you are not willing to put in the very large effort to buiild a site on the keywords above you can always specifiy the niche. An example of this would be, instead of Travel Insurance, create a Web Site on Travel Insurance Companies based in Denver, Colorado. You will not recieve a diversity of hits  since it is a specified niche, however, the more unique the site, the easier it will be to achieve a higher Search Engine Position, and you will be able to see progress quicker than with a larger scale site..