The topic of tracing recursion in Scheme came up at today's SICP study group meeting. It can be done with Dr. Racket.
Here are the relevant docs.
First require trace:
Then trace the function that uses recursion:
A complete example from SICP:
I recently went to a great meetup on regular expressions in Vim. Here are a couple of links I found during the meetup:
YSlow for Phantom: