1. HootSuite - Social Media Dashboard for Teams using Twitter, Facebook, Linkedin
HootSuite - Social Media Dashboard. With HootSuite, you can monitor keywords, manage multiple Twitter, Facebook, LinkedIn, Foursquare, Ping.fm and WordPress profiles, schedule messages, and measure your success.
http://www.hootsuite.com

2. Posterous - The Easiest Way to Post and Share Anything
Posterous is the easiest publishing platform around. If you can email, you can manage a website and share it with small groups or the world.
http://www.posterous.com

3. twitterfeed.com : feed your blog to twitter
Feed your blog to facebook, twitter, and more!
http://www.twitterfeed.com

4. TweetDeck - Your social world
TweetDeck is your personal browser for staying in touch with what’s happening now, connecting you with your contacts across Twitter, Facebook, MySpace, LinkedIn and more.
http://www.tweetdeck.com

5. Twellow.com
Twitter users organized into business categories. Search for Twitterers and find new ones to follow based on common interests.
http://www.twellow.com

6. Ping.fm / Update all of your social networks at once!
Ping.fm is a simple and FREE service that makes updating your social networks a snap!
http://www.ping.fm

7. Manage Social Networks with Email - Constant Contact NutshellMail
Receive all your Facebook & Twitter updates through a single email for free. Our updates also support Twitter Search, MySpace, LinkedIn, and Email Forwarding.
http://www.nutshellmail.com

8. twe.ly - Shrink your link!
Shorten any URL so it easily fits within Twitter's 140-character limit.
http://www.twe.ly

9. Shozu.com
From Mac or PC, upload your photos and videos to your chosen online communities from Facebook to YouTube, Twitter to Flickr and so many more.
http://www.shozu.com

10. twhirl | the social software client
twhirl is a desktop client for the Twitter microblogging platform, powered by Adobe AIR.
http://www.twhirl.org

11. Create a Social Networking Site with Ning, the Best Social Site Platform
Build a social destination to create a community. Foster conversations, drive action and earn revenue. All in a matter of clicks.
http://www.ning.com

12. Twply.com
Receive your Twitter @ notifications in your Inbox!
http://www.twply.com

13. Social Media Management, Twitter Tools, Social CRM | Sprout Social
Sprout Social provides comprehensive Social Media Management tools that enable you to find new customers and to grow your business. Try it for Free.
http://www.sproutsocial.com

14. DandyID: Universally Portable Social Identity!
Simply put, DandyID allows you to store your various online social identities in one place!
http://www.dandyid.org

15. beyondWP
Facebook Registration Plugin for WordPress
http://www.beyondwp.com