Keyboard, 'gaming' mouse (high DPI), and an Xbox360 controller. More I do not need for the PC.
In the good old past when they made flight and space sims worth the time (Wing Commander FTW) I had a great joystick as well, but that broke down ages ago and isn't supported any longer anyway.
For sound I have my 5.1 speakers and a good headset for late night gaming or team-based multiplayer.
On the console end, I bought a custom PS3 controller that has the Xbox layout so my thumbs don't impact all the time and my fingers are on the right buttons/sticks in rest position, and I got the PS Move controller in a moment of stupidity. I've yet to see anything making worth its cost besides casual games like Darts and that block stacking game.