An interesting concept: a programmable debugger for MzScheme (the platform of DrScheme). Essentially more of a monitor - it observes the running program and, based on specifications in scripts, can trigger various actions. For this, a variant of Scheme specially optimized for event control is used. This appeals to me because I typically don't use normal interactive debuggers - somehow they're just not my thing. I prefer to let programs run and collect information during the run. In Lisp, something like this is already quite elegant to implement - just wrap functions accordingly (or in Common Lisp use advise to bind debugging code to functions). MzTake simply extends this concept further.