The best way of promoting your site or blog on the net is through email marketing. let's face it that it is the number 1 killer approach for marketing on the internet today. The cost involed here is very low but the outcome is very high.
There are numerous mass mailers called opt-in mass mailers where the members have agreed to receive emails from you. You just have to compile a good email and send it with the click of a button to many recipients. The yahoo and google groups use this strategy. A list of good mass mailers can be found through yahoo and google search.