I liked the Ribbon a lot before I got used to the Mac mentality of "reduce buttons at all costs". Ribbons work far better than lots of drop-down menus when you're dealing with something ridiculously complex.
OS X used to have an awesome theming app called Shapeshifter, which doesn't yet work for OS X. There was one ultrapervasive theme called Gaia that I've always wanted to play with and couldn't, since I came in on Leopard. Check it out: http://macthemes2.net/2007/08/10/theme-review-gaia/
EDIT: Dammit, its Gaia theme is a third-party remake that's very glitchy. To its credit, it didn't delete system-crucial files when I removed all the testing themes.
OS X used to have an awesome theming app called Shapeshifter, which doesn't yet work for OS X. There was one ultrapervasive theme called Gaia that I've always wanted to play with and couldn't, since I came in on Leopard. Check it out: http://macthemes2.net/2007/08/10/theme-review-gaia/