I use a couple of tools/plugins to keep my install clean.
- power tools to clean spam comments and splogs
- a non-wp script to optimize and repait the db
- a non-wp script to mail users who have not psoted anything or not logged in in a certain time that their blog will be deleted if they don't use it
- manually mark blogs as archived and if nobody complains delete them after a couple of months
- use another plugin to re-send activation key and delete old unused ones
how about wrapping all that in a nice plugin?
I know you guys usually tend to stay away from dangerous stuff... still, some of these funtions could be really useful.
ehre is my +1