If you seeing the popular blogs, news portals, and websites having one button “like”, “share”, “follow us”.. Some of the sites servicing the junk of social connectivity icons.
If you want to setup those icons on your pages on manually, you can. Below i have listed some top sites.
Facebook badges: http://www.facebook.com/badges/
Tweet button: http://twitter.com/goodies/tweetbutton
StumbleUpon badges: http://www.stumbleupon.com/badges/