Sensitive Number Finder

Do you have personal data, like credit card numbers, on your HD but are not sure where?
This free app might be useful to you. Works on all platforms.

Edit (25-06-08)Ç
I tried this today and it certainly works.
The terminal command is

java -jar senf.jar

to be run from the directory where senf.jar is installed.

Actually, it picked up quite a few "suspects" but all were false positives. But, better too many than too few.
Lots more info in the wiki.