For my SOAP talk at chicago-pm I wrote a small current awareness utility (googling) that will query google's SOAP service and send any new results via email. The idea is that googling can search for new stuff that you are interested in, and email you when if finds new stuff. It can be run from cmd line, or more usefully from cron:
googling --query="link:www.inkdroid.org" --email="firstname.lastname@example.org" --key="yourgoogleidhere"
This would use your google key to search for all the sites that link to www.inkdroid.org, and will email email@example.com with any new sites that it finds.
The program recognizes new sites because it remembers what it has seen before on previous runs for that specific search. The memory is of course a little database, implemented in SQLite (ahhh). googling creates the database on the first run, so there's no need for you to create it yourself. You just have to have DBD::SQLite and SOAP::Lite installed.