With the rise of all the new social sharing technologies like flickr, digg, and flagr, the web is getting back to its roots as a community building and content sharing medium. Yub.com brings social tech into the field of shopping, and once you've seen it, you won't be able to go back to Web 1.0 commerce again.
Yub's motto cleary maps out what you can do there, Meet.Hang.(and)Shop. Generaly when shopping for something, you usually are faced with at least 2 major problems: what version of the type of thing that you need are you going to buy (what product) and how can you get it at a good price? Yub uses collaborative techniques to solve both these issues, allowing you to network with people to get advice on products, and sharing their affiliate revenue with you if you make a purchase. There are lots of major sites they are partnered with like Target.com, Buy.com, and Dell.com, and if you buy after going through Yub, Yub gives you back anywhere from 2 to 25% of the purchase price. (The range may vary more, those are just numbers I plucked from scanning the site).
You can't argue with the value of getting a discount while shopping. It's great, and the main reason to use Yub. Hopefully at some point the knowledge sharing, networking part of the site will offer the same value. I was disappointed in the section where you could Meet People and the Raves/Fan Clubs area, both of which seemed more like place holders that vibrant communities. There is an Advice and Deals section where people post coupon codes and notices about deals that seemed a bit more useful, but the main draw is the cash back Yub gives you on the sales.
I'm not sure how long this will last. More and more merchants are skeptical of rewards sharing programs, and they could stop their association with Yub at any point. While it's functioning though, go give it a try.