When I got home from work yesterday my
Playstation controller adapter was here. Now I can use PS2 controllers on my PS3! Before you ask why I'd bother seeing as the Dualshock design is pretty much the same for both systems, this adapter lets me use my PS2 Saturn pads with the PS3, as well as my X-Arcade stick. I played some online MvC2 yesterday and it was pretty cool until I ran into a "Storm/Magneto/Ironman infinite juggle whore" player.
There are other adapters out there, but this one supports vibration, has the PS Home button on it (also allows you to hold Select and hit Start to bring up the XMB) and most importantly is 99.999999% lag free. I had zero timing issues putting in commands and was able to do all my usual combos in both MvC2 (PSN download version) and Street Fighter III: 3rd Strike. Apparently it also works for PC gaming but I have a wired 360 controller for that, but I digress. The point is it works perfectly and is awesome.