I haven't had much luck with Renoise yet (haven't gotten a chance to play with it yet). I did find another program I don't think was listed yet that looks promising:
Jeskola Buzz
http://www.buzzmachines.com/getbuzz.php
And a free loop mixer that is easy and interesting to use:
Rubber Duck
http://www.d-lusion.com/DownloadRubberduck.html