clipped from: www.refocusingtechnology.com   
TweetLater (http://tweetlater.com) is another great third-party Twitter tool that makes tweeting easier on the time schedule.  There are a ton of great features in TweetLater (some of which I will highlight below), but the main function of it is to be able to punch out a ton of tweets and schedule them to hit Twitter at some time in the future. 

TweetLater also does many other things.  You can setup follower functions, such as sending auto direct message replies, track keywords, setup un-follow  rules, etc.  And with new enhancements coming all the time, I always look forward to how I can utilize TweetLater next.