Games

• Tweep Tycoon - Buy Twitter users as pets and grow your social portfolio. Be the richest social tycoon on Twitter!
• Trivia on Twitter A hot new Twitter-based trivia game where people can win real prizes every round just by tweeting. A leaderboad is updated every 10 minutes and is cleared after every round, so new players can join in when they please. Check it out: http://triviaontwitter.com
• Trivtweet Trivtweet is a twitter daily trivia game that tests your knowledge of Film and Music stars.  Daily questions over three decades per category. 
• GuessWord - remember Mastermind? Well this game is similar. The GuessWord server hides a word and you try to guess what it is. Tweet any word to @GuessWord and you will get clues to the mystery word within 20 seconds. Be the first to get the points. As a never-ending game, a new round is constantly created after one completes.
• FlockPoker - With FlockPoker you can create your own Texas Hold 'Em poker table and invite people through one simple link. It's easy and free, try it.
• QuizTwit - The super fun pop-culture themed quiz game. Earn points redeemable for prizes. Just follow @QuizTwit to play!
• TWord_Chains - A morphing word game where you change one word into another following rules. Played with tweets so that people know when a chain has been changed. A word chain is like: MILK ... MILE ... LIMES ... SLIMED. This game is co-operative rather than competitive.
• Tweet Words - A tweet-based mystery words games. Clues are tweeted to followers about every 5 minutes. Tweet back with your guess. A leaderboard is maintained. Follow @Tweet_Words to get your clues. Once the current word or phrase is complete, a new one starts automatically.
• Tweet Quiz - A tweet-based quiz where you must find hidden words and phrases using clues that are periodically tweeted. For example, a challenge might entail "Things associated with a Volcano" or "A meal or food made with Eggs". Tweet your answers with an @reply or play on-line. Slight misspellings are tolerated.
• Twetris - A tetris like game that uses the latest tweets from the twittosphere as blocks for the game.
• Twirl of Riches [beta] - A phrase guessing game in gameshow format similar to hangman. (By @TwtGames)
• Which Twitter Celebrity Are You? - A fun quiz. Answer a few questions and we'll tell you which celeb you are most similar to!
• Whose Tweet? - A game that tests how well you know your Twitter friends. Can you figure out whose status message this is?
• TweetTest - A collection of 6 mini-games that use data from your public Tweets.
• Tweetaways - an easy way to pick a random person who has tweetwed a specific phrase.  Handy for drawing winners on free giveaways on Twitter.
• Who Has More Followers - Play the game : How well do you know the top twitter users? Choose which of the randomly presented top tweeters you think has the most followers.
• GamerDNA - track gameplay from Xbox Live, Steam, Xifre, etc., and rebroadcast to Twitter.
• SkillPod.com - The Twitter app Tweets all your game play, sharing your favorite games with your friends.
• TWord_Chains - A morphing word game where you change one word into another following rules. Played with tweets so that people know when a chain has been changed. A word chain is like: MILK ... MILE ... LIMES ... SLIMED. This game is co-operative rather than competitive.
• Tweepshoot - A Wild West Shoot-em-up on iPhone that tests how well you know your friends. There's also a list of the most wanted spammers, and players can brand their own spammers to help out in the war on spam. Follow @Tweepshoot to find out more.
• Twrivia - Daily trivia quiz. Dispensing useful topical trivia. Prizes some days. Answers and players' leaderboard are shown at the website: http://twrivia.com
• TweetMyGaming - real-time feed of everything game/videogame related on Twitter.
• Twetris - A tetris like game that uses the latest tweets from the twittosphere as blocks for the game.
• Twirl of Riches [beta] - A phrase guessing game in gameshow format similar to hangman. (By @TwtGames)
• Twtpets - A simple twitter game for pet lovers. Upload a picture of your pet. Share it with your tweeple via a short url. Vote on the cutest pet. Disclaimer: All pets are cute! No username/password required. (By @twtapps)
• Which Twitter Celebrity Are You? - A fun quiz. Answer a few questions and we'll tell you which celeb you are most similar to!
• Tweetaways - an easy way to pick a random person who has tweetwed a specific phrase. Handy for drawing winners on free giveaways on Twitter.
• TwitterBox -- a Twitter client for Second Life.
• SLTweets.com -- a Twitter HUD for Second Life, includes mapping, notes, research, SLURL logs. On or off modes.
• TinySL.com -- a Second Life specific SLURL builder and long SLURL or Second Life compression too so Twitter users know the content is relevant or an in-world (metaverse) destination.
• Squawk -- A Twitter client for Second Life. Also supports Ma.gnolia, del.icio.us and Jaiku. Integrates with Squawknest, a web component with user profiles, tagging and web maps.
• Sl-Messenger.com - A global IM/twitter/diary service for Second Life.
• The Nerdiest Tweep - How nerdy are you?
• BraveBalls! - Multiplayer RPG.  Hack through infinite random dungeons, vanquish hordes of monsters, and tweet about it!