Is there a bookmarking service that allows users to organize bookmarks into folders, groups, or tags, and more importantly, allow users to export bookmarks from an individual folder, group or tag?
PS: As should be very clear from my question, the exported file should be browser-compatible (Chrome or Firefox) so that I can simply import them into my browser at will.
FYI, I've tried Delicious, Google Bookmarks, Diigo, and Kippt. Services like Evernote and Springpad are out of question, as all I need is a simple bookmarking service.