A mix of SEO, PPC (but not much anymore as it truely is sucky traffic), forum postings, business sized postcards we hand out to everyone, linking with high quality relevant sites (yes for traffic as much as the PR). Voodoo is doing a great one (I assume to be article submission), a great source of traffic and Google does love all of the one-way links, plus the extra content for your site doesn’t hurt either. You should also consider having a newsletter that visitors can sign up for and receive regularly from you, make sure you have something worthwhile to say though.