Sun Poker has been online since 1999 and has a very good name. Asides from the normal things that you find at online poker rooms - the difference with Sun Poker is the $500 No Deposit welcome bonus that they offer which works as follows:

To welcome you as a new player to SunPoker.com, you can receive up to a whopping $500 in your first month of play, without having to make a deposit! You won't find anything like that in a land based poker room. How it works: Download the free SunPoker.com software and get into the poker room and start playing your favorites like Texas Hold 'em, Omaha and 7 card stud, and you're on your way to free and easy money. Your free money will be released into your poker account based on generating certain levels of MPPs (My Poker Points) Read more about this on their website