mdutil
mdutil lets you manage OS X’s Spotlight indexes from the command line.
If you notice Spotlight’s mds process using up a lot of CPU, erasing and rebuilding the indexes for all volumes can fix the problem:
sudo mdutil -aE
Or, if you want Spotlight to stop indexing a particular volume (a backup drive, for example), run the following:
mdutil -E -i off /Volumes/MyBackupDrive
