fseventer allows you to graphically observe filesystem changes using the same underlying API as Spotlight. One example of use could be to determine what files are changed via software installation, preferences, etc…

What’s new in this version:

Version 2.1:

* Leopard support - including new XATTR fsevents, and official FSEVENT API.
* Ability to save results as log files.

Version 2.0:

* New GUI - with table view and file inspector.
* Now tracks all events, up to 10000.
* Experimental function to list all open files.

Website
Download fseventer