Well... mods? There are lots of them, just check
the modlist.
If you want a new exciting adventure with new areas, try
Dungeon Crawl. If you'd like to try new NPCs with banter(and new quests), try
Angelo,
Xan,
Keto,
Kivan.
If you want new romances, half of these NPCs are romanceable, and there're new romances for Bioware NPCs, too, like
Nalia de'Arnise romance. The writing is indistinguishable from the original game.
And if you'd like new fun cool interludes and adventures for any PC, try
Romantic Encounters. You won't be disappointed.
Or play
EasyTutu with
BG1 NPC - an entirely new cool game.