Delicious is a useful tool. I use it in an unconventional way sometimes: I bookmark some resources with tags which serve as indicators for my backup tools. As an example, when I tag my Gliffy diagram pages with the my-diagrams tag, my backup tool grabs the corresponding diagrams and makes local copies on my server.
The backup tool I am referring to is readily available here. I configure the backup tool to run periodically through cron jobs on my Linux server.