You can hack flash games such as Bloons Tower Defense, tanks, etc.  All you need is a a program called Cheat Engine 5.5 (download: http://tinyurl.com/CheatEngine55)

Heres a video tut on how to use it. All credit goes to Col2eight.
How to Hack Flash Games - Ex. Bloons Tower Defense 2

Some good flash games: http://www.miniclip.com/games/motherload/en/
                                    http://www.ninjakiwi.com/Games/Tower-Defense/Bloons-Tower-Defense-2.html
Some good flash game sites: http://www.miniclip.com/games/en/
                                          http://addictinggames.com/