Check out various charity fundraising auctions too. You could donate a certain dollar value of portrait photography in exchange for the advertisement and promotion of your name on the auction brochures.
You could also do this with many non-local fundraising auction events by donating a print for them to auction off.
For example, your local PBS station. Does it have an art auction like mine does?
Here's a link to my local PBS station's art auction website so you can get an idea of what's involved.
http://www.kvie.org/events/artauction/default.htm
Here's the link to their call for artists page with all the forms and legal stuff involved. For this particular auction, the submission deadline is coming up in a few days, but use this as an example of what else to look for and what other possibilities may be out there for you.
http://www.kvie.org/events/artauction/callforartists/default.htm
One good thing about this particular auction is you don't necessarily have to donate the framing. They have framers donating materials and services for that too.
Here's a description of the call for artists from their website:
Quote:Participate in the KVIE Public Television Art Auction 2008 juried open competition and your art will receive unprecedented exposure in a televised event seen by up to 60,000 motivated art-buying viewers. The Art Auction will be heavily promoted through television, direct mail, web, and live events well in advance of the 3-day telecast.
Enter your best work and you'll have the opportunity for recognition in this highly competitive, prestigious juried show that attracts the very best Northern California artists. Emerging artists as well as established artists get the opportunity to win valuable cash prizes.
The art that will be offered includes works from the juried open call, along with pieces from selected participating galleries, and from a group of established artists who contribute to the artistic excellence of our region.
Enter your work and be a part of our community's most comprehensive art event of the year.
And here's a link to their online auction website where you can view the art, bid on it and watch live streaming of the auction show when it is broadcast on TV.
http://www.kvie.org/events/artauction/art_auction_07/default.htm
If other PBS stations have these, there's a lot of opportunity for exposure and name recognition for your work.