just how helpful are they? i see people trading delicious bookmarks for cash on a variety of sites, but does it really help? if it was that easy to get stuff bookmarked, i'd think engines would have stopped caring about it a while ago... am i right?
It helps get pages noticed, but the direct benefit is zero, because delicio has rel-no-follow on the links. For webmasters delicio is one place to check for links to share, so if you can get your link noticed you're one step closer to getting a link from some blog or link-site that may want to link to your site. But if your content sucks, that's still not going to happen.
If you hit the delicious popular list it sends thousands of visitors as I reported last week on http://www.blogstorm.co.uk/blog/week-one-stats/