"Limit poker is a science, but no-limit is an
art. In limit, you are
shooting at a target. In
no-limit, the target comes alive and shoots back at
you."
- Crandell Addington, Poker Hall
of Famer/founder World Series of Poker
There are hundreds of poker variants and new ones are being created all the time.
Every poker player has their favorite draw, stud or community game. Sometimes the games fall into more than one category. You can still find the rules to Spit in the Ocean online, along with hundreds of other variants with names like Wall Street, Psycho, Cowpie Poker, Iron Cross, Round the World, Dirty Schulz and Pass the Trash.
Seven Card Stud, Omaha, Razz and Lowball are other popular variations that you can easily start playing after learning Five Card Draw and Texas Hold 'Em.
Seven Card Stud - This traditional variant is played with two hidden cards and one card dealt face up before the first round of betting, three more upcards (with a betting round after each card) and one more card dealt face down, with a final betting round. Players can only see three of the seven cards. The best five-card poker hand wins the pot.
Omaha - This variant is growing in popularity and is similar to Hold 'Em, using a three-card flop and a Turn and a River board card. Each player is dealt four hole cards and can only use two of them plus three board cards to make their hand and win the pot. Omaha involves lots of multi-way pots, frequent raising and is considered a game for action players.
Razz - The lowest hand wins the pot. Straights and flushes have no ranking and the best possible hand is a low straight (5, 4, 3, 2, Ace).
Lowball - The lowest hand wins the pot in this draw poker variant. Each player is dealt five cards face down and players have to open with a bet or a fold. Active players can improve their hands by replacing cards in the draw.
You can see an extensive list of poker variants at Pagat.com.