Application Switching suggestion

I love Quicksilver, and have used it for years now. I still keep
LaunchBar running on my machines for just one thing: Application
Switching.

I love that repeated hits of cmd-space (or whatever your trigger keys
are) brings up a drop down that steps me through my running apps. Two
slaps switches between the top two apps in the stack. It's a great way
to go back and forth between two, as when needing to copy from one and
paste to another.

If Quicksilver had this feature I'd be able to abandon LaunchBar
completely.

Thanks.