FriendFeed Read Later Greasemonkey for Firefox
FriendFeed Read Later is a Greasemonkey script that allows you to mark entries to read at a later time, easily accessible in a custom tab.
The script adds a "Later" button for each entry. Clicking it will make that item available inside a custom "read later" interface tab, and also simulate a "Like" action for it. To remove read items, simply click "Done!" - that simple!