Google, Yahoo! and MSN (Live) all have webmaster tools that require
users to verify that they control the site, either by uploading files,
or by adding meta-tags.
I never liked adding meta tags, and I found it hard to keep track of
whose accounts the uploaded files pertained to (in case I ever wanted
to revoke access - not that it matters much). So I wrote a small
plugin to handle verification files and keep track of the codes in a
single yaml file.
Nothing ground-breaking, but saves a little time if you work on lots
of small sites and also handle seo tasks.