You already have a Stumbleupon account. You can share your hubs at http://www.stumbleupon.com/submit but unless you have followers no one is going to read them. Get followers by reading other pages, making comments, and then they might follow you.
If you have already submitted a page to Stumbleupon, I do not think it does any good to resubmit it. Just get more followers.
The same goes for Pinterest.