I don't get that many visitors on my blogs. I haven't got much time to blog and even less to market them, so the number of visitors are quite low.
Still I think StumbleUpon is an amazing tool worth investing into.
Buy after reading several threads in BlogCatalog about StumbleUp, I decided to test it. I create a little post and went on asking my buddies at BlogCatalog to stumble it. The result was instant:
The big spike in my Analytics is from stumbling Breaking New: Whole Foods Market launched in London on Business Matters. You can see the effect: big rush of visitors (about 200 compared to a normal 4-5!). Sadly they don't stay very long (about 1-2 minutes) and don't stick either. Still I think StumbleUpon is an amazing tool worth investing into.
You must design ways to get them to come back: email/RSS subscription sounds like good idea, you could bribe them with freebies as well. Another option if you are into making money is to ask your buddies continuously to stumble your post (although they could get bored of it) as you will get spikes and spikes of visitors. If you have ads for instance that pay per view it is not a bad thing at all!
If you actually wanted to use it for yourself as opposed to just increate your traffic; basically you need create an account, then you should really install the FireFox toolbar for StumbleUpon and then you get lots of new buttons; 3-5 of them really matter.
One is called "Stumble", when you click this, you get instantly a new page loaded. The pages I believe is selected from the the interests you listed on StumbleUpon while creating your account and from the people stumbling pages. The 2 next important ones are "Thumbs up/down" which tell StumbleUpon if you liked what it showed you. I supposed the software behind must refine the selections based on your input. Finally, if you are nice guy or gal, you want to review some sites using the "Review" button which will give them more exposure because the reviews will appear in StumbleUpon are visible to all users.
All in all, StumbleUpon despite looking a little bit nerdy, is a great tool to give a boost to your Analytics ratings and also a cool way of visiting sites you will not normally look at.