Xpadder: Play PC games with a game controller instead of a keyboard
XPadder emulates a mouse and keyboard with the buttons and directional thumbpad of your game controller.
Many casual Web or Flash games would do well to implement gamepad controls. Platformers and bullet-hell titles are a perfect example. Sure, you can get by with WASD and the space bar, but it's not 1992 anymore. You shouldn't be forced to just get by when you've got that shiny, $60 wireless gamepad sitting two feet away. The answer here is a program called Xpadder ($10).
Xpadder emulates a mouse and keyboard with the buttons and directional thumbpad of your game controller. It supports multiple profiles, rumble feedback, and chorded input, which allows for more commands than the number of buttons would normally permit. This technique can also be used to refine emulated mouse movement, with quick or precise modes for the analog directional stick switchable by toggling a preassigned button.
Configuration screens are easy to decipher and present you with a visual representation of your gamepad for easy key assignment. You can also use it to control desktop software: For example, the video player of your Media Center PC can use your wireless controller like a remote. Xpadder isn't currently free, but it's well worth the money developer Jonathan Firth is asking. Older, free versions are still around if you'd like to give a try before purchase.