I think you should make plurchase completely public, so that I can see everyone (and they can see me). That way, I don't have to invite my friends to shop + I can spy on other people (making it fun even when none of my friends are online).
We plan on supporting both public & private. Mostly just UI work to add the public functionality. One idea: when in a public shopping group/room, we'd replace the little preview boxes with a stream of just-product-pages as people visit them.
you can also keep track of how people browse the site from page to page, etc. and draw lots of good stats. e.g. similar to amazon's "people who bought these also bought..." or "people who viewed this ultimately bought..." but globally across multiple sites
Yeah, we can have all kinds of fun things once we have a few thousand daily users. We could do stuff like: pair you with other camera shoppers if you're interested in cameras specifically, allow you to help other people shop for specific things (personal shopper), find out what people ultimately purchased when they looked at your current product, what other stores users visited when looking at the current product, etc