I use KRunner for launching most of my apps and it's a pretty efficient way of doing so but I reckon it could be a much more powerful desktop tool if it had richer user feedback and interaction. I've made some mock-ups which are shown and discussed in the blog linked to below:
I'm sorry for the rambling blog, brevity takes practice and skill.
http://maninalift.blogspot.com/2008/12/k…-interface.html
P.S. Sorry for the heavy reference to Mozilla Ubiquity, note I'm not simply suggesting copying its design pattern.
Cheers.