Trade On The Dark Markets (Facebook, Twitter, LinkedIn)

Have you ever wanted to buy shares in companies that aren't available from Scottrade or E*TRADE (NASDAQ: ETFC)?

Now you finally can, thanks to new sites like SharesPost and SecondMarket that have opened the market to private investments.

Facebook, Twitter, and LinkedIn are among the hottest private companies being traded.

With more than 33,000 institutional and individual investors, SharesPost allows its users to manage the purchase process on their own or request the aid of a Transaction Specialist, who will complete the transaction for them. SharesPost says that its specialists are FINRA-registered brokers who are available to assist members with all aspects of their primary and secondary transactions.

SecondMarket, which touts itself as being the largest secondary market for alternative assets (including private company stock, limited partnership interests, and asset-backed securities), says that its market specialists streamline the process from listing to settlement.

So while investors can't yet acquire Facebook stock on the open market, they do have alternative options that can enable them to get a piece of the social networking giant years before its IPO.