What's with all the little social networking icons at the bottom of every page?

These are called 'Service Links,' and they link your page to a variety of social networking sites.

By going to Site Configuration> Service Links 2, you can adjust how you would like them to display, on what types of content, or if you would like to disable them all together.  By clicking the ’Services’” tab, you can decide exactly which social networking sites you would like to display.