If you've never heard of StumbleUpon before you came across its mention in Piece of the Fame, it's definitely time to get started using this powerful tool!  As you read, StumbleUpon is the #2 traffic referrer to sites amongst all social media platforms!  That's HUGE.  The following video gives you a quick overview of StumbleUpon Ads and enough information to get started with their quick and easy process.

And just so you get a good idea of what StumbleUpon is as a platform, here's a very short overview video produced by the StumbleUpon team.

I've found StumbleUpon to be a quick and easy platform to use.  Although I use is more for advertising than I do for time spent in discovery across the web, I think that this platform is going to become increasingly important and visible in the near future, and people start to look for more specific and curated discovery experiences relating to their use of the Internet.  Enjoy and Best of Luck!