This is an obvious one, but I'll lodge it just the same!
Now that you guys have added the indexing feature, it make a lot of
sense for this to be open to Spotlight searching, to really integrate
your Del.icio.us research (what-have-you), further into your workflow.
Usage:
It would be fantastic to be able to search the indexed content of the
pages I've bookmarked via Spotlight, so that I might be able to find
that reference to a particular research paper, effectively alongside
the PDF of the paper I downloaded, an email exchange on the
subject, my notes, other reviews/critiques, and links to web pages
from my browser's history.
Whoo hoo! ; )
On the downside, I'm guessing that your index is not separate file,
like Spotlight requires, so it probably wouldn't be a small issue.