Havelock:
havelockinvestments.comWhile MPEx is also a solid (and secure) option, some of the less-experienced, less-endowed crowd have trouble with the interface and registration fee.
On Havelock, equities are issued in BTC and pay daily/weekly/monthly/quarterly dividends. Most are prices in the 0.00X range, but they also have ASICminer passthru shares, a difficulty derivative (runs by twentyseventy) where you can buy and short mining power (leading to a zero-sum speculation game), a real estate investment fund (Rental Starter), a number of mining projects (notably PETAMINE and Scryptx by Cryptx), a passthru of Rockminer (the miner manufacturer) shares, and a few more speculative funds.
Definitely, DEFINITELY do your research here on the forums and with outside resources before investing BTC. There are a lot of factors involved from the issuer's level of transparency to the funds' business plans and the nature of funds' underlying operational assets.