I came across this app while mucking around with the latest Kubuntu. It is a program launcher. You hit alt + space then type for example, kmai. By now it should show you the kmail app and all you need to do to launch it is hit enter. It should normally sit in the tray, in case it does not, you can hit alt+space and then control+c to configure it. It is a neat app, try it out.
Home page : http://wiki.thekatapult.org.uk/Home
Kde-apps page : Link