Recently I sat down with a well-connected Silicon Valley CEO who just raised a ton of money, and who knew of other startups raising even more. There is a new startup club of younger companies raising money right now at $1 billion valuations. I already knew a couple of them, but I started asking a few venture capitalists and now I have a pretty good list of who is in that club and who is trying to get in (see below). As we all watch the established Web companies go public ( LinkedIn , Pandora ) or prepare for an IPO ( Groupon , Zynga, Facebook ), there is this new class of younger, but fast-growing, startups rising up right behind them. A lot of them are out raising money right now at $1 billion valuations. These are $50 to $100 million rounds, and they are generally going to companies showing incredible growth rates in both users and revenues, at least according to investors who have looked at these deals. So who is in the new billion dollar valuation club?