You can: - list your program with the affiliate program directories. - create an optimized page for "product-keyword-phrase affiliate program." - Look for affiliates on your own, and send personalized emails. - Get creative, try something like cross promoting your program with another similar themed, but non-competitive site that has a program.
If you sell gadgets, optimize a page for "gadget affiliate program" (or similar keyphrase - do your research.) When I am looking for an affiliate program for a site, one of the first things I do is go to google and search for something like that. I'm sure other affiliates do the same.