My devotion to Google Reader has been well-documented here, and I relish any new opportunity to get more of it (though I'd have to be a superhuman to read everything in my reader daily).
Read It Later is a free Firefox extension that just adds little empty check marks to stories in your feeds, and when you come to a post you want to read but don't have time to, simply click the check marks.

All checked stories are then saved in a separate reading list — either from Read It Later's site, in your RSS Reader, or for reading offline later!
Yes. I love this extension!
1I downloaded this extension on Thursday, after CNET.com reported about it. I use and LOVE Google Reader as well; and this extension on firefox is very useful. There are many things I read that helps with this purpose.
I highly recommend this extension to anyone, even if you do not use Google Reader it is very useful.
You can watch a short demo video on the site that explains the extension.