You should check out linkies.com - disclaimer I'm a co-founder. Anyways linkies organizes your posts/bookmarks based on the hashtags you use. You can even group hashtags into groups that we are calling grashtags. You can also subscribe to just the topics you are interested in to create a custom news feed of links updated by the people you trust. it's currently in private beta but let me know if you want early access and I will see what I can do.