One thing some people may miss from other operating systems is desktop widgets. There's several ways to get these in Ubuntu and its derivatives. For Gnome users, there's the gdesklets or screenlets packages. For KDE3 users, there's superkaramba, and if you're using KDE4 there's plasmoids available - just add the extragear-plasma package.
Now there's a new way to get desktop widgets, and this way gives you access to a huge cross-platform library of widgets. This is of course Google Gadgets. It's long been missing from Google Desktop on Linux, but now it's available separately.
I'm not going to tell you how to set this up because the people at Ubuntu Unleashed have written a great guide to this, which is available here. You should already know how to add third-party repositories, so I'm comfortable leaving you to head there if you want to install Google Gadgets for Linux.