You're limited to only your own imagination [img]smile.gif[/img] Most things that aren't there can be added. If you're interested in anything that has to do a bit with scripting, which I think you'll anyway, the
NWN Lexicon is the place to start. Be sure to do the tutorials by Celowin, they rock.
ALso there's a script generator by Lilac Soul which could be handy as well, so I hear (don't use it myself). You can find it on the Vault.
Have fun!