And how about someone makes a gun that shoots bullets on left click, rockets on right click, N for nukes, T for torcreeps, and A for airstrike?
Theres a blade bow out there already I think.... I remember messing around with one.
Look at any weapon at all that has an alternate fire for how to detect the trigger, then something like Ephialtes' Shotgun or the Tank Turret on how to spawn projectiles.