SocialOomph.com is a service that provides free and paid productivity enhancement services for social media users, including Twitter.com and other social networking sites.
Base features are many: Schedule tweets — Plan, set & forget (Twitter, StatusNet); Schedule tweets and keep your Twitter and StatusNet streams ticking over with new tweets even when you're not in front of your computer. Publish tweets when you know your international followers are online and you're asleep; Track keywords. Set up alerts and track keywords in the public Twitter stream. SocialOomph will monitor the Twitter tweet stream and periodically email you a digest of the tweets that contain those keywords. You can also use this to track your @replies; Extended Twitter profiles. Promote yourself – expand your profile area on Twitter – SocialOomph enables you to write your own long and detailed social profile (including pictures and hyperlinks), and link this extended profile to your Twitter account. When folks click on your “Web” link in Twitter, they come to your extended social profile that is hosted on the SocialOomph site.
Free, $29.97 for SocialOomph; Professional Edition for a fee.