Wow, no mention of the Wizardry series....
I've just re-installed Wizardry 8 (I had the first seven games in a shovelware pack, but can't find them...argh!) and am having a blast and a half. Great system, and good, clean graphic presentation (if not technically awesome).
I miss party-based games like that. It's the reason my favorite of the old Black Isle AD&D games was Icewind Dale. The ultimate for me would be a party-based Roguelike....