As mentioned, Avant Window Manager (AWN) is a really nice osx-like bottom menu (http://awn.wetpaint.com/
) - you need to build it from source if you want the best functionality.
Kiba-dock is another nice one (http://www.kiba-dock.org/
Both require a composite manager of some kind. I use xcompmgr because it's lightweight and I find Beryl and Compiz incredibly unstable on my video card.
gdesklets has a nice menu applet, but I have found problems making transparency work properly in gdesklets.
Using the standard gnome panel but making it not auto-expand is probably a lot easier, but doesn't give quite the same effect!