MintMenu (which is a fork of Slab) is one of the best Linux main menu's I've seen. We already reviewed it HERE (click for a lot more info and screenshots).
We've decided to pack MintMenu and upload it to its own Launchpad PPA (there are no other packages in the PPA except MintMenu) which you can add using the following command:
sudo add-apt-repository ppa:webupd8team/mintmenu && sudo apt-get update
And then install MintMenu in Ubuntu using the following command (Ubuntu 9.10 Karmic Koala and 10.04 Lucid Lynx only!):
sudo apt-get install mintmenu
Once you install it, right click on a Gnome panel, select "Add to panel" and then search for and add "MintMenu".
The package in the MintMenu PPA is the latest version which comes with the latest Linux Mint 9 Isadora.
MintMenu is also available in the WebUpd8 PPA - a PPA where all the packages we will be publishing to different PPAs will be copied (except VLC - no more VLC in the WebUpd8 PPA).