Get an Optimus keyboard... Oh right, we can't yet! Damn, that keyboard's been in development for 3 years...
Anyway, I use an Ideazon Zboard, allows up to 7 simultaneous keypresses, and features 2 built-in USB slots for extra devices. Works great for me.
And for a mouse, I use an Intellimouse Explorer, 7 buttons. I have a Logitech MX-500 or something like that, but, the additional buttons aren't as configurable.