The hits that you get from SU maybe nothing more than using up precious bandwidth, but when your starting out and want to get your site noticed, its a great tool. Having just a couple of people "like" your site, you could potentially have thousands of hits/pg views in a very short amount of time. If you are an established/well-known website SU doesn't offer much cause of the low conversion rate. Either way, its a great way to attract a diverse audience to your site.
if you can't get decent position on Google or Yahoo then social bookmarking is your greatest traffic source
Lol I wish I was you, SU sends me thousands of hits and then they all like my stuff so more come Anyway, I preffer SE traffic, its much better.
SU can give you awesome traffic but ------------- weird, there was no clicking on my Adsense! let say I got 200 visitors from SU, but my adsense still not in profit btw, you still can selling your products through SU that's cool!
its all about the keywords. make sure that you choose the correct category and then select popular keywords.
I can surely write you some tips here, but due to my laziness I will just give you a link to one of the post in my blog, showing how to get traffic from StumbleUpon.
If you're looking for an ego boost, which is like mental masturbation, then stumbleupon is right up your alley. You have to remember what this traffic is. People click on a stumble button and it takes them to a random page. Traffic isn't going to be sweet. But if you're right into stroking your ego with your traffic stats. Go for it. Call me crazy or "old fashion" but the only stats I care about are the ones with $ signs in front of them.
I've found stumbleupon to be OK, you get a steady stream after you've been stumbled, and if more people thumbs up you it picks back up again.
How many people realise that stumbleupon has a prefetch system that means many of the apparent hits have never been seen by human eyes - your site is merely being queued.
As long as you receive visitors, you may find other ways to monetize them, even when they don't look at your page (CPM advertising).
It will increase your unique visitors, but if you check your stats. you'll find that most of the visitors stays less than 5 seconds... unless you have a long interesting video... It's the nature of the button, you just keep stumble 100's of pages by clicking the button.
The traffic I've generated from stumbleupon hasn't been targeted... I have other methods which have a much better return on investment... so I stopped stumbling