I've tried many ways to easily share items from my browser to any of the social networks I'm using. Addons came close to working fine but I always worry (maybe unreasonably) about their load on the browser.
Then, I came across bookmarks (or bookmarklets) via a Scott Hanselman's post and I found a winner.
Here are the code snippets for how to share to some of the popular social networks. Simply create a bookmark and provide its location to be the code snippet:
To send items to Kindle, use Klip.me