I recently came across in an internal newsgroup a couple great sites that provide lots of code samples for expressions and runcommands. You might find this useful.
Terry Wickenden's web site has lots of examples of RunCommands:
Brendan Reynolds has a great blog where he researched what functions can be used outside of the Access environment.
Lots of good developer content...
Edited on 3-6-2007. Terry provided me with a new URL.