What's the best branding opportunity for a venture capital partnership? Conference sponsorship looks desperate. Fancy office space inappropriate. But Peter Thiel's Founders Fund has hit on a good spot to display its initials: on an entrepreneur's share certificate. The iconoclastic venture capital partnership, which has invested in startups such as Powerset and Engage, offers "Series FF" stock to founders . Its special power? Entrepreneurs, who usually have to wait until a public offering or a rich acquisition before their common stock is worth anything, can sell Series FF shares in a subsequent venture round. As a sweetener for cash-starved and impatient entrepreneurs, Series FF is attractive; as a trademark for a new VC firm, it works too.