I don't think shopping mashups have a whole lot of value. Unlike the social shopping sites popping up everywhere, mashups aren't very community oriented and simply recycle data from other sites. I think a combination of a mashup and social shopping may be the way to go, but I just can't see a plain mashup winning over many shoppers.

Jason, I tend to agree. There is only so many ways you can mix Shopping.com, Amazon.com & eBay. Mainly saving it for future reference, to see if anyone will add any interesting layers to the existing data sources. (Thanks for the comment, by the way.)