All scripts mentioned here are for CS3 and later unless stated otherwise.
InDesign CS4 added 37 Unicode GREP wildcards (\p{P*}, \p{Lt}, etc.), which brings the total number of wildcards to more than 50. How do you know which characters are matched by which wildcard? The "grep mapper" shows you.
InDesign's Find what field must be one of the smallest and unfriendliest places to write and edit GREP expressions in. But it takes surprisingly little effort to turn InDesign itself into a GREP editor. (Rewritten November 2009)
Following on from the system described in the previous point, here is an alternative, much simpler GREP "editor".
Print a report of all GREP styles defined in a document's paragraph styles (CS4 and later).
The script prints an overview of all GREP queries on your system.
Find/Change queries can be saved in the Find/Change dialog. Unfortunately, you can't chain queries. The script remedies that: you can select any queries and the script will execute them one after the other.
The script can be used to test GREP expressions as well, by collecting all found instances and showing them in a new document.
Questions, comments? Get in touch