Actually, here in San diego they have something called the free dental clinics... i'm sure they have some in many of the major cities across the country. For this one here in san diego, it's actually affiliated with the university of california, san diego, and we have three clinics. The volunteers (mainly made up of pre-dental students) are able to do anything from managing, to scheduling patients, to doing front desk work, to taking x rays on patients, taking impressions, etc. 99% of us aren't RDAs (there's only one in our club that i know of) and other than anything you actually need to have a dds/dmd for, we can do everything else. Many of us have gone and obtained xray licenses for the state of california.
I know there are opportunities like this (i went to a katrina thing similar to this and i was a DA), and if you're interested in starting up a free-clinic thing similar to the one that we have at UCSD, you can check out our website:
http://www-acs.ucsd.edu/~ucsdfdc/index.php
i might get crap for advertising about our club but in all honesty, i think it'd be great if other people had an opportunity like ours.