"Oh, I don't have time to read all these interesting pages now. Can I find them easily and continue my reading?"
Don't worry! Diigo provides a very handy Read-later feature for you.
Click Read Later button on the diigo toolbar.
Check all your unread items in the unread folder of diigo toolbar or in "My library".
(Note: same action as checking "unread" checkbox on the bookmarking window.)
Here is a short "how to use Read-Later" tutorial: