You can buffer your tweets directly from Google Reader (please don’t ask me what is buffer)..
At the bottom of an article you will find “Send to” button. If it is not visible, then go to “Settings”, then select Reader Settings. In reader settings, select “Send To” tab. Here you can select sites where you want to send your shares.
In this list you can find a “Create custom link”. Go ahead and click on that.
Now enter following details:
Icon URL: http://bufferapp.com/images/logo_icon_small.png
Done. Now click on “Send to” and select Buffer from list for any post you want to share over tweeter via Buffer.