third party tools to audit spreadsheets

[Dave F]

Here's an open-ended question:

What third party tools do you recommend to audit spreadsheets? I'm aware of
Walkenbach's Power Utility Pack, and am looking for other tools to augment
the built-in auditing capabilities of Excel.

Specifically, I am looking for tools which can help diagnose formula
discrepancies/logical errors/etc. Obvisouly no tool can fully eliminate
errors from occurring in financial models but surely there are some tools out
there which are more robust than Excel's built in functionality.

So, have at it: what do you recommend?

Thanks,

Dave