Ask HN: Founder/common stock purchase agreements?

I'm incorporating my startup and would like to issue some common stock. The only agreements I'm finding though (YC's Series AA, Techstars' docs) are for the purchase of preferred stock.

Is there an "open source" common stock purchase agreement?

Edit: I think I found one here: http://www.orrick.com/practices/corporate/emergingCompanies/startup/forms_founders_stock.asp