Spectating tables (especially Poker)
Would love to see a spectate option added to tables so that we could watch games play out (with the HUD and camera angles we're used to seeing).
It would aid in helping newer players learn some of the more complicated games (The instructions for Craps even walks you through an example game), and would do wonders for the social aspect of games, namely poker.
Personally, there have been some poker games that I wanted to watch until the end - and did, or at least tried to. The numbers and pips on the cards are so small that, even in first person view, it's difficult to identify a card whose pips are obscured by another card. Heck, even un-obscured, I can barely tell the difference between a Heart and a Diamond.