>What is this telling me? Is this an execution trace? What do the leading
>numbers mean?

The report is a tally of message sends and the percentage of overall time 
taken in each.  This is done by setting a timer to interrupt the "spyed 
upon" process every so often and examine the execution context.

> Are there any other neat tools like this in Squeak?

Sure!  For example, MessageTally also impelements "tallySends:", which 
simulates the block, counting the exact number of message sends.  Try:

     MessageTally tallySends: [3.14159 printString]

Maybe other folks will pitch in with their favorite "hidden tool" in 
Squeak.



     -- tim