My Tweet Map - Displays a list of the latest tweets of people you follow on a map. Your stream is on the sidebar, just click on a tweet and it will take you to that users location. Most of the other Twitter map services are on auto-pilot, I liked the simplicity of this one. You can reply to tweets and post a new tweet.
Tweet Later - this service does a few things: a Twitter reminder, auto-responder tweets to new followers and an auto greeting tweet, and schedule 12 auto-tweets an hour…for more auto tweets see TweetResponse, TweetAhead, AutoTwit, and for more reminders see ReTweetMe and Twitter Timer.