Craigslist.com has somewhat of a deserved reputation in that many of its readers are looking for cheap/almost free goods and services. In the 'Artists', 'Creative Gigs' and 'Event Gigs' sections, which are the ones I frequent, there are always ads seeking out student photographers, muralists, graphic designers and what-have-you. The potential customers desire to pay little or nothing in return for experience or the career-enhancing "you'll have something to put in your portfolio..." not realizing or caring that the quality of work they get from a beginner will not measure up to that of a professional.
While I am all for student artists of any type learning their craft and temporarily asking for commensurately less in compensation, my philosophy is that the artists themselves (and now I particularly mean caricaturists) should choose their beneficiaries. When I was starting out, I did free caricatures for my children's schools and friends and branched off into paying work from there. That way, one's inexperience is not detracting from the whole profession, since your family and friends know that you are just starting out. The downside to working for next to nothing for real clients is that it causes an expectation that all caricaturists be in that pay range...
That being said, I still post ads on Craigslist and have gotten some gigs from it.
My most recent one is reminding people that summer parties and caricatures go together perfectly!