Just saw a note on the Rhizome mailing list about this. Every member on Rhizome has their own RSS feed now. If you go to a member page you’ll see a link that under Member RSS feed that you can subscribe to. This is a great idea i hope it takes off. Maybe this is a possibility for mnartists.org in the future.
Also they added a feature to find users by location recently. Unfortunately it only lists people down to the country so the US listing with 400+ people is not extremely useful, but if I lived in Greece with only 3 members it sure would be nice to find the other two.