I know not everyone checks out the Blogger Buzz! but they've been doing some neat things lately and one of them is the new Share button on the Blog navbar. If you look up at the very top of the browser window you should see a bar with a B a search box, and then some buttons. There is a new button up there, "Share". If you click that, it makes sharing the entry you're reading. Want to tweet about your friends latest post? Click Share, then twitter, and you're all set!
Check out the article in the Blogger Buzz for some other nifty things you can use the share for...like in your Google Analytics, or watching people share on Twitter...its kind of funny the amount of people using the link to tweet their own posts.