Currently the most functional PS2 Pad Plugin, created by ChickenLiver. This one has proved very popular providing support for keyboard, mouse, gamepads, xbox360 controllers,PS3 Dual Sock 3 and multitap!

For the changelog, as well as support, visit this thread
http://forums.pcsx2.net/thread-2388.html

The source can be downloaded from the official svn repository of the pcsx2 project hosted at GoogleCode: http://code.google.com/p/pcsx2/