Personally, I use a ZBoard (Which I think is now part of Steelseries, honestly). The swappable keysets are kinda clunky, but I can't play an FPS without the "gaming" keyset now. It's just so much more comfortable. If this one breaks, I'll probably see if I can find a ZBoard Merc - no swapping keysets. Full keyboard with a gaming keypad on the left.
