Launchy is a free multi-platform keystroke launcher built mainly to make it easy opening files and applications instead of using your standard start menu, file manager, app shortcuts, etc. Launchy can index all applications in your start menu to let you launch quickly your documents, files, home and system folders, web page bookmarks, etc.
To try it under Ubuntu 11.10/11.04, open the terminal and run these commands:
wget -O launchy_2.5-1_i386.deb http://goo.gl/qDQo6
sudo dpkg -i launchy_2.5-1_i386.deb
For Ubuntu (64-bit), install it with these commands:
wget -O launchy_2.5-1_amd64.deb http://goo.gl/FTYvj
sudo dpkg -i launchy_2.5-1_amd64.deb
You can then start it from the Unity Dash. You can customize Launchy from the Options window:
For more Ubuntu launchers, you may also try Gnome-Pie.