The Fallout 2 Restoration Project unofficial patch, which adds a whole mess of things that didn't make it into the official release due to the lemmings not jumping off the proper cliffs in the proper order...or something...Things that were still included in the programming but not implemented until some brave and bored soul took the time to fish around in the guts of the game and reel them out.
Anyway, I never realized just how big the Fallout 2 world was compared to Fallout 1, having mostly just breezed through it the original time I played and not really playing much differently any successive trips through, in so much as I never really went continuously out of my way to thoroughly discover all the little secrets hidden in the nooks and crannies of the game. Actually pretty impressed with how much stuff was left out of the official version. Hell, there's even a few Red Dwarf references, which pleasantly surprised me. (There's a bit where you find a broken toaster, and after you repair it, dialog lifted directly from a Series IV episode ensues *points at his signature below*)
If you're needing a Fallout fix, I'd recommend downloading this mod/patch if you haven't given it a try yet!
~Narf!