Maybe Facebook and MySpace are a little to edgy for you but don’t lump Linkedin into that equation. The average income of a LinkedIn member is $150k+ per year. This is geared to professionals and is the largest online professional networking site out there. It only takes a minute to set up a free account and will safely search your contacts to see who is already on Linkedin making getting started very easy.
Linkedin is now supporting some plugins that will allow you to put your content in front of your connections which will also be accessible to their connections and your potential audience. The plugins integrate with WordPress Blogs so when you update your blog or post a new article your Linkedin page will proudly display it for you. They also give the option for a status update that functions very similar to Twitter, notifying your viewers of what you are working on.
I use a service that makes updating all of these social networking sites much easier. Ping.fm is allows you to send one message and have it land on your Twitter page, Linkedin page, Facebook and many more. You can use this to promote your business, product or whatever.