Most design/development forums have place for members to post ads like our very own commercial exchange forum [webmasterworld.com] ;)
These are a great way to meet budding freelancers, and discuss projects and to see their portfolios. As most designers tend to have a online portfolio a few well targeted pleas will get you enough urls for you to pick and choose the person with the right skills and experience.
Another avenue for you to explore are job agencies who specialise in finding work for designers (In my experience the bigger more general agencies send few qualified candidates). they will have a list of designers working freelance and can put you in contact with them - the one big limitation with this over 'net'working is paying the agency a fee but it can uncover a gem - We found an excellent freelancer this way who works full time with us now.