Here's another free option that I've used happily for some time now if anybody is interested:
http://rbtray.narod.ru/
And here's a mirror, since the original site is on some free Russian hosting place and seems to be frequently unavailable:
http://www.preater.com/apps/rbtray/
All it does is make it so when you right-click on the minimize button of an open window it minimizes to the tray instead of to the taskbar.