What are these links?

Del.icio.us, Digg, StumbleUpon and Reddit allow you to store, tag and share links with people you know & people with similar interests. Clicking on the their links on the Buy Tracks section allows you to bookmark and comment on this part of the website.

How can I use them?

You need to firstly register with each site if you don't already have an account. It's free and only takes a minute or two. You'll then be able to use them when you have logged in.

For more information visit the Wiki page on Social Bookmarking.