I've loved Reddit.com from a viral / incoming traffic point of view, but you've got to be a broad contributor, ensuring that you post non-business content and interact on other's contributions. If you only self-promote, you'll quickly get banned from the "sub-reedits" you really want to post to.

It helps to make sure your customers and friends know when you post on reddit. Organic "up votes" can take your links from getting a few hundred hits to 10,000+.

Hope that helps!

Ken Clark
Coach, consultant, and therapist to entrepreneurs