Many went to direct shares, like LRM did. A few are exploring trustless trading systems using the block chain to verify transaction (ala OgNasty/NastyFans) and keep an automated list of shares (fee-free trading). Most were essentially group buys, so their securities are designed to fall to zero value and not much needed for exchange.

Some are actually doing zero-fee direct share exchanges over the forums (ADDICTION). I cannot recommend tyrion70 and blastbobb enough, if anyone is interested in group buys in the future - their operation is amazing, I'm very happy with them.