PS Tray Factory will allow you: hide low-activity icons from a system tray into menu, hide inactive icons from a system tray into menu (as in Windows XP), get fast access to the hidden icons with the help of hot keys, change the order of icons in the menu, hide from the menu seldom used icons, restore icons in system tray area at crash or restarting Explorer.exe.
More info:
hxxp://www.pssoftlab.com/

Not bad. Even better maybe compared to Mike Lin's Traysaver?

I'm not sure. Anyway I have run Traysaver for quite some time. It gives you the same possibilities, but it's free and made by a real nice guy. He also got some other interestening utils, click away to /www.mlin.net and have a look.