Here is a fine project which is providing mac-like additions to the gnome desktop. I first tried the old repo and had difficulties installing Globus-Preview. After some discussion on launchpad I eventually was given a solution which worked right out of the box. The new ppas are here. Definitely gets my vote for inclusion in the next official edition of Ubuntu.
Gloobus-Preview , the quick and easy previewer for your files
Gloobus-Flow , browser your files with a Coverflow-like effect
Covergloobus, desktop widget for displaying cover art of the currently playing song. Comes with lyrics and controls for your favorite music player
Add the new ppas
NOTE: There are new PPA for gloobus, and for covergloobus
sudo add-apt-repository ppa:gloobus-dev/gloobus-preview sudo add-apt-repository ppa:gloobus-dev/covergloobus