There are many different styles of variable names that I've come across over the years.

The current wikipedia entry on naming conventions is fairly light... 

I'd love to see a concise catalog of variable naming-conventions, identifying it by a name/description, and some examples. 

If a convention is particularly favored by a certain platform community, that would be worth noting, too.

I'm turning this into a community wiki, so please create an answer for each convention, and edit as needed.