Stumble Upon Advertising Program

I got an email a few days ago (as I am sure anyone who has used the StumbleUpon Ads did) talking about features, and new enhancements to come with the SU advertising program in 2009.  Here is part of the email sent:

More Reasons to Start a New Campaign More traffic to your website

* More traffic than ever: The StumbleUpon community continues to grow—Stumbling over 4 billion times in 2008 and actively viewing Websites—including yours!

* Improved Advertiser Resources: New detailed information on how to use StumbleUpon to drive paid and organic traffic to your site, including a Top 5 tips for Advertising on StumbleUpon.

* More Advertising enhancements coming later this spring: Increased targeting capabilities, enhanced reporting and even more control in driving a targeted, pre-qualified audience to your Website.

I share this because I would like to hear from other people their thoughts on the StumbeUpon advertising program?

My Successes:

I have had great success with it as far as gaining readers and subscribers to blogs, but other then that I have not found a better use.  It also has its obvious uses for getting the word out, generating buzz and gaining links, which in turn helps out the SEO of course.  The reason I think its one of the best sources for gaining new subscribers to your blog is because it can be super targeted and you can hit just the right audience.  I can honestly say that I have made money from the SU ads to, because I have had people that have bought product tell me they first heard about the product via Stumble Upon.  Granted that does not happen a lot, but I thought it was worth sharing.

I will keep using it to get the word out about blogs I am promoting, and finding a good reader base, but other then that, my use of the program ends there.  Any other uses or ideas that you guys have experienced?  I would love to hear about them.