Had to add my two cents as an avid gambler.  For poker Seals has good ring volume, but BetcoinPoker has exceptional tournament liquidity and I have been able to actually earn somewhat of a living the last few weeks playing poker there.

For casino, BetcoinCasino is my favorite place as the experience is truly high end and better than many non-bitcoin casinos, let alone bitcoin casinos.  I also enjoyed just-dice and satoshidice.

For sports, I enjoy Nitrogensports and BetcoinSports.  Great experiences at all the websites mentioned and high end customer support on all.