Thumb manager
http://www.thumbmanager.com is an excellent script, I have 5 copies of it. Andy and Matt are also 2 great people to deal with, very helpful and knowledgable. The script doesn't have all of the bells and whistles of Comus, but it does great for me.
There's also Smart Thumbs, I've heard a lot of good things about it. People say that it does what Comus does, but doesn't have all of the complication to it, Comus is a nightmare at first until ya learn it. Anyways, here's a link to Smart Thumbs -
http://www.thumbsrotator.com/index.php?s=man