There is something reassuring about a weighty keyboard. I can actually give mine a prod... the same prod that sends my mouse about three inches across my desk, and this keyboard moves about 2mm. But then it does weight nearly 1.75kg!! If you pick it up by the keypad it's actually quite difficult to hold...
http://www.keyboardco.com/keyboard_details.asp?PRODUCT=646 (except I'm a gimp and have Red WASD and Escape mwhaha)
Decided that the mechanical keyboard is the way to go. I tend to type a lot more than most people do, and to be honest I wear keyboards out quite rapidly (point, my work keyboard is mirroring up quite nicely now and I've had that a year). The best part about this one is every few years I can just replace the caps when they get all manky and give it a good clean down.
http://www.keyboardco.com/keyboard_details.asp?PRODUCT=806Want one of those too... Though, with blank caps. I know where all the keys are after all!

Yep, the actions do make a difference, the switch types alter how the key presses work.