The best social bookmarking and general Web exploration tool that I've come across lately is definitely Stumbleupon.StumbleUpon is quite different from the previous social bookmarking services that I’ve talked about so far, in a couple of important ways.
First, the emphasis is definitely on sharing great sites with the greater StumbleUpon community. You can do this simply by installing the StumbleUpon toolbar. As you come across great sites that you would like to bookmark and share, you hit the Thumbs Up button on the StumbleUpon toolbar, give the sites a few quick tags and categories (this is to help other Stumblers find what you’re about to submit more easily), and then click Enter. That’s the social bookmarking/social networking part of StumbleUpon.
However, the reason why I’m so utterly enthusiastic – and more than a little addicted – to StumbleUpon is this: I can wander from site to site within the StumbleUpon gigantic submitted database of Web sites. All I have to do is click the Stumble! Button on my toolbar, and I am able to explore the Web like I’ve never been able to explore before.
You have a couple of options as you're Stumbling through the Web as well; you can choose to discover sites from any category, or, you can narrow it down to either predetermined topics or a topic of your own choosing.
For instance, the other day I was interested in looking for Harry Potter sites, so I entered in the term “harry potter” in the StumbleUpon search bar. Instantly, I had some of the best Harry Potter Web sites around available to me, along with quite a few that I had never seen before (and quite frankly, I’m not sure how easily I would’ve been able to find them on my own).
That’s the beauty of StumbleUpon, to my mind: you are able to take advantage of a vast network of dedicated Web searchers who are finding utterly brilliant sites and sharing them with you. I do have to warn you, though – StumbleUpon is an incredibly addicting way to search the Web. I found myself up till 1:30 AM one weekend, blearily clicking the Stumble! Button over and over again, because the quality of the sites are just so amazing; you just keep on coming across stuff that instantly merits a bookmark of your own.
I highly recommend using StumbleUpon both as a social bookmarking community and as an absolutely vital Web search tool.