The king of thumb tgp scripts is
http://www.my-teensex.com/tmanager/ . It will rotate your thumbs and find the best spot for the best thumbs. Your productivity will soar. I'm pushing around 100K/day through Thumb Manager at panty-ass.com. Other webmasters are pushing over 500K/day through it.
I can also recommend
http://www.xclicks.net. It's a free remotely hosted traffic trade and thumb rotation script. You can't receive submitted galleries through Xclicks, but it works very well with sponsor hosted galleries putting the most clicked thumbs in the top position. I have Xclicks running at akissbetweenthelegs.com with around 50K/day.
Other scripts that rotates thumbs and ranks them according to productivity:
http://www.easyteenpics.com/thumbnail-preview-script/
http://www.the-best-tgp.com/hspics_script/index.html
http://www.mdue.com/turbothumbs.html
http://madthumbs.com/madscript/
http://www.nibbi.net/scripts/comus_thumbs.php
... and some thumb tgp scripts that - as far as I know - doesn't rank thumbs according to productivity:
http://www.jmbsoft.com/software/agp/
http://www.germesia.com/scripts/brownie/index.html
http://www.adultdevil.com/scripts/ultrathumbs.shtml
http://www.tgpxs.com/