a good poker multiplayer?

Texas Hold'em on facebook is a good one.

PokerStars PLAY app on facebook - BEST !

register at Pokerstrategy and recieve a 50 $ start gift for some pokersites like william hill etc... you can't play directly with your friends, but you will learn it the right way through this site, and the winnings you get out of the 50 $ are yours. real money.

Here are the sites and the boni you get:
Coral Poker $45
Titan Poker $35
William Hill $35
Betfred Poker $40
NetBet Poker $50
PKR $45

Tabletop Simulator maybe?

irl

PokerTH
Open source cross-platform.
Windows, Linus, MacOSX and Android.
And it's free.
But it's just for gaming. No gambling. They don't (or have plans to) deal with money.

Pokerstars