Create a a flyer & mail it out. You can contact your local post office for rates on this, or pay someone to give them away. If you're advertising mortgages target areas with households. Anyone who has a house is a potential client for mortgage refinancing. Anyone who lives in an apartment might be house shopping. A business card is also a good idea. These methods are obviously only available if you're located in the USA. 

One cannot underestimate the effectiveness of PPC (pay per click) search engines. Promote your program of choice when someone looks up anything mortgage related such as 'mortgage refinancing'. The leading PPC search engine is currently Overture, they power the sponsored results for Yahoo & MSN, amongst others.

If you're patient you could always try the time tested method of SEO (search engine optimization) this method is free, but it may take months until you're listed high. To get listed high you should visit our SEO Tools website.