Nice screenshot!
* calcdude keeps waiting for a public demo 
Pausing the emulation at every in a,(01h) and in a,(c) when c is 01h could be interesting... It could be an awful pain at times, but I guess it could be useful.
If that's being done, then Wabbit should probably highlight the keys corresponding the selected groups (what keys will be checked on the read from the keyboard). For example, the code "ld a,FEh \ out (01h),a \ nop \ nop \ in a,(01h)", which checks the arrow keys, would highlight them upon reaching the "in a,(01h)" line.
Edit: Nevermind, there is one (demo). I just hadn't reached the post yet
