Boot selector

If anyone's ever used bootcamp, they know it gives a tray icon in windows that lets you choose which OS you will be booting into. I had an idea that this would be a great idea for us who use multiple OSes. It would be trivial to rearrange the boot.ini file in 2k and later, but anyone have any ideas on how to implement this in other OSes? I would assume it would have something to do with the active boot partiton but i am probably way off base. If anyone has any ideas or would like to help, i would appreciate it. For my personal use, just being able to rearrange the boot.ini default would be ok, but i occasionally have other oses on my other drive.