Brand new Playstation controller(either PS1 or PS2) to USB converter/adaptor.
Use your Playstation pad on your computer, just plug it in & you're ready to go.

Supports everything = all 12 buttons(including triggers), both analog sticks, d-pad.
Can use any buttons simultaneously.
Will work the majority of Playstation controllers / steering wheels / wireless controllers, but I can't guarantee compatibility with every controller brand/model.

Works with PS2 wireless controllers I'm selling(as at December 2010).

Dance mats work fully(can press left/right, up/down at the same time), if the optional drivers are installed.

Vibration feedback(controller vibrates, same as in some ps2 games) supported, if the game supports it. Requires the optional drivers to be installed.

NOTE: Pressure-sensitive buttons on DualShock2 do work, but only as on/off buttons(not pressure-sensitive like when used with a PS2)

Compatibility is identical to a USB joystick, so will work with practically every game.

USB, Plug & Play, no power supply needed

Compatibility:
Driver software(only needed for vibration feedback, or using dance mats) = for Windows only, should work for versions up to Windows 7.
I can email the driver software if needed, the manufacturer didn't include driver disks in the package. All other features work without installing drivers.

Using builtin drivers:
Windows 98, Windows Me, Windows 2000, Windows XP, Windows Vista, Windows 7. Any version of Windows after Windows 95 should work fine(as they support USB)
Linux, MacOS, OSX etc = will almost certainly work with any modern operating system.

No driver software needed, it works with drivers built into the operating system(convertor works immediately after it's plugged in, no installation needed).

USB socket on your computer is required (almost all PCs have this)

Won't usually(if at all) work in DOS mode, just like other USB controllers. DOS mode is only important for very old games(made before about 1997).

Cable length: 50cm

Note: for some reason, this shows up as 2 controllers - but you just use the first one in the list. It doesn't cause any problems.