Some programs exist to allow you to use game console controllers (such as the Xbox 360 controller, or my usb-connected SNES pads and dual-shocks) to play games that don't support controllers natively. This can really help if the keyboard and mouse give you RSI, or the game was originally designed for use on a console.
I'm currently using ControlMK. It works (mostly), although sometimes one of the analog sticks and/or some of the buttons will not work once you are actually inside the game, and the configuration can be very complicated. Plus it doesn't work with every controller, nor every game (probably the game's fault, to be fair)
So to summarise, How can I easily setup different game controllers to work for multiple games by emulating the keyboard/mouse?