Try this app for managing followers- http://www.chirpless.com (free)

One of my favorites is Twello (www.twellow.com) Using Twello can also help improve rankings.  It gives you detailed statistics and lets you build a profile for your site. (Also free)

I use Hootsuite for Twitter to tweet and schedule (www.hootsuite.com).  It gives the nicest interface and the smoothest experience.  You can keep track of mulitple Twitter accoutns with Hootsuite- without confusing yourself! 

I would also highly reccomend Ping.fm.  You can ping different social networks, including blogs and greatly help SEO.  Most times, you set it up and your tweets, blogs, and other posts automatically ping the server.  It does all the work for you!