If you could have one Valve weapon irl, which one would it be?

Sgt Pepper Wrote:
True, Valve rather buys small compagnies with great idea's then come up with their own. CS:S, Portal, L4D, TFC, all made by outsiders who later on got hired by Valve. Ow well, at least they give the modding community some hope of ever making money on their hobby's.