When we go out and train our clients on how to get the best use out of the various social media platforms one thing we like to do is show them how all the various things connect.
The image below (larger PDF here) shows how we feel each of the various websites/services can either feed into each other, or be used to drive traffic from one to another.
If you look closely, the website cloud has only inbound arrows. Whilst this is not necessarily the only way of looking at this, it's our preferred way.
All the other sites, your blog, your LinkedIn profiles, Twitter activity should all be used in the main, to drive traffic to your website.
If you need any help in understanding this spaghetti map, please do get in touch.