Mr.doop’s Hi-ReS! Stats is a must have for every ActionScript developer. Seems to be still no. 1!
And I don’t want to search again… So here just the links:
Mr.doop’s blog | Hi-ReS! Stats
Mr.doop’s Stats.as @ GitHub
Update – Most recent version I found:
http://code.google.com/p/mrdoob/source/browse/trunk/libs/net/hires/debug/Stats.as