I have my bookmarks on the cloud (delicious firefox extension). I have delicious show up as a bookmark toolbar instead of the Firefox toolbar. I choose Favorite Tag view and then I have three tags as favorite: 1-frequently used bookmarks, 2-less-frequently used bookmarks and 3-Read later articles. I tag lengthy articles with the third tag and they stay there in front until I'm done reading I would simply remove the tag.

The only thing missing is the reminder or stay fresh alert. Sometime it takes some effort to go back to old and lengthy articles.