One place to pick up a crew position would be at the jump off for the Atlantic Rally for Cruisers. The ARC departs from Las Palmas de Gran Canaria and crosses to Rodney Bay, St.Lucia on 21 November, 2010. Or look around Gibraltar, France, etc. in the Med. Here's the web site, Atlantic Rally For Cruisers
Please do your research regarding your own visa status before you approach a boat. You need to be sure you have the correct papers to enter a country before you leave, otherwise you could penalize the entire boat should you need a visa and don't have one.