On Web bookmarking

The use cases I need for a web bookmarking application are:

• Quick button or key combination to bookmark an URL.
• Review bookmarks for obsolescence. Each bookmark should be checked periodically to find if the resource still exists and have a notification when it does not exist. Bookmarks should have attached a review date to be able to review bookmarks one by one.
• Retitle bookmarks. (Many times the title on the page is not the one I want)
• Classification. I do not like hierarchical classification because many bookmarks may own to more than one category and hierarchical classification can only have one folder structure. (Example: low fat meals/fish or fish/low fat meals) (tags also have problems as it is common to tag an AJAX tutorial as "AJAX,JavaScript" but AJAX already contains JavaScript implicitly on it but I want to get that page when I look for the broader term like JavaScript resources)
• As bookmarks refer to online resources they may only be accessed online, but I still need transparent backups in case the online resource that hosts my bookmarks accidentally removes them or just disappears.
• Pending revision. I sometimes see something that I need to review but I still do not want to publish in my public bookmarks.

I am currently using delicious.com to host my public bookmarks, but that solution alone lacks reviewing and quick bookmark saving (unless you use the fat Firefox plugin).