How Does StumbleUpon Help Bloggers?

Yeah, I feel a little bit silly and sheepish about it, but I must admit that I don't really get StumbleUpon.

The idea behind the site is pretty simple: a downloadable tool bar add-on allows you wander around the Internet (via pressing the Stumble button) with the presumption that the more you interact with the tool (rating sites along route with a thumbs up or down) the more it knows what you like and helps you to discover cool sites that you would likely never find on your own.

I get that part. It's not something that I would personally get into, but it's a nice little service. Where I start to lose grasp is in understanding how StumbleUpon has become "a substantial driver of traffic," as Mathew Ingram and many others have noted, and how publishers are supposed to take advantage of the site to harness the stumblers.

Getting the toolbar installed and logging into StumbleUpon was a somewhat clunky experience for me, but perhaps that was an aberration. Figuring out what to do next as a publisher was, however, where I really got lost. I was eventually able to figure out how to submit a site URL, but I was left confused as I've seen other writers note how they've used StumbleUpon to drive traffic to individual stories.

After spending a fair amount of time investigating, I realized that there's a tagging feature in which you can add tag words to individual "pages." I'm not sure if adding tags to an individual "drilldown" story page in effect submits that story into the StumbleUpon system with those tag words attached, or if you're simply associating tag words with an entire website or blog.

I like to think that I'm a relatively savvy Internet user, so if I'm confused, I'm guessing others are as well. For non-publishers, for those people just looking to stumble around and find cool sites, the service is likely less of a headache to figure out. But I'm genuinely curious to hear from bloggers who utilize StumbleUpon as part of ongoing promotion efforts. Is it necessary to tag your own pages every time you publish a story, for instance? Or is some other action involved?

There's also a social networking side to StumbleUpon where you can find and socialize with other stumblers who have interests similar to your own. Again, I'm guessing that there are those that find this to be an engaging feature, but I've never really believed that social news or social bookmarking sites have an overwhelming amount to offer in terms of social networking. In other words, when I visit Reddit I'm interested in finding stories that I'm into and don't really care connecting with others who may be as well. Maybe I'm just a curmudgeonly electronic loner though, who knows?

A standout exception to this is MyBlogLog, which does a great job of building community around the blogging experience, playing into the inherent need for bloggers to self-promote and connect with fellow online scribes.

In any event, I'd love to hear from those who have had some experience with StumbleUpon, particularly from the publisher/promotional perspective.

In essence: is there more to get than I've gotten?