Since RSS Feeds have become so popular there are many
options available these days for utilizing them.
Bookmark4U is an excellent example of a prefect use for
RSS feeds. A cron could run every so often which goes
through the B4U database and creates RSS feeds for each
user. Then those users could use RSS Readers and
'instantly' read their bookmarks from their browser,
such as using Firefox Live Bookmarks feature.
Something along the lines of
b4u.domain.com/rss/user.rss would be good I think, and
of course only public bookmarks would go into the RSS,
and the user should have the option of not having an