I think it would improve the power user experience if you could “type-to-focus” when using Expose, at least it would to me 
What I mean by “type-to-focus” is that if I invoke expose, I get a collection of windows that have a title attached to them, being able to focus on them by starting to type their name would make it even faster to navigate between windows. Alternative you could also switch the focus by using the arrow keys (similar to “Overview grid”).
Hope this hasn’t been requested before, I couldn’t find it while browsing the forums.