I found it annoying (and battery consuming) that my PBG4 constantly accesses the disk due to the indexing of files, as I never need to search for contents within files.
In 10.2, in /System -> Library -> Find is a file called SkipFolders. I edited it (as root or change ownership before/after editing) and added a "/" at the beginning of the file. This got me silence from then on!
[Editor's note: Untested, but it makes sense based on the contents of the file.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20021024063705938