When you throw a weapon such as a throwing dagger and spear, and it hits the enemy, does it stay on the ground for you to get back, or can you get it back on the corpse. I want to see if this works, or if i have a bug. Im playing fallout 2.

Throwing knifes and spears, rocks, etc, stay on the ground, you can get 'em any time you want. Things like molotov can't be recovered, for obvious reasons (unless you're playing Megamod, where molotov lose it's explosive damage. It's like throwing rocks.).
Some times a item can get hidden in a corpse or building (very frustating).

Also note that the items don't *always* drop to the ground. This seems to be more common with daggers than with spears, but I've lost spears after throwing (and hitting) an enemy as well. Daggers have a tendency to get stuck underneath corpses or gibs in addition to disappearing. My guess is that there's a chance for them to get destroyed, so you won't have a 100% recovery rate.

That said, my character that specialized in throwing (as a low-AP backup for my big guns) used explosives almost exclusively... molotovs in the early game, and grenades galore once I'd stocked up on them.

There's a simple joy in a well-placed plasma grenade.