The sibling to this by jrumbut has great suggestions! Personally, I made some good client connections through other freelancers in different markets, like video FX and graphic design. They often have clients that also need dev work. Or, sometimes you can find people who want it but don't know it yet; you can start a good conversation like, "you know, there's some good tech out there to add X to your site, so you or your customers could do Y much more easily." Sometimes business owners don't even consider some of the options available to them through commissioning custom software!