Eject is a little dingus you can keep in your Mac’s Dock. Click it, and it’ll eject all disks except the startup disk, as well as an iPod if iTunes has one connected. It’s just a little AppleScript packaged as an application with a nice ejectish icon. Download this, unzip it, drag it to Applications, and then drag it into your Dock.
I use it to eject external drives (mainly my Time Machine drive) before I pack up my MacBook Pro to take it on the road.
(I could have sworn that I posted this before, but I can’t find it, so… )