Spotless is a $8 OS X utility that lets one delete spotlight (oh wretched implementation) indices and disable spotlight indexing.
In theory Spotlight has a mechanism for excluding drives from indexing. In practice it doesn't work. OS X is perpetually trying to index an external backup drive -- no matter how often I tell it not to. Spotless claims to have disabled that indexing and to have deleted the files.
Unless 10.4.4 finally fixes that blasted bug, and assuming my problems with that drive resolves, I'll happily register spotless.
Oh wretched Apple that three bug-fix releases of the 10.4 have not fixed this problem.