Paul Krugman takes a stand in support of taxing financial transactions. He mentions activities in the financial sector that Adair Turner referred to as "socially useless", meaning especially speculation. I'm all any means of reducing excessive speculation, if a workable solution can be found.
On the other hand, there could be more talk about encouraging more socially useful activities. Investment must be directed away from speculative secondary markets and into primary markets that create new real assets.
There was a failed attempt at getting tax relief for "angel investors" in Finland. The idea was quite sensibly dropped, because an "angel investor" is not a concept that anybody is able to define in a watertight manner in a legal sense.
So I thought: Why not give a tax relief to all capital gains income from first resales of stock that was bought in an issue. Thus, the original holder of any newly issued equity would have a favorable treatment. This would both create an incentive for participating in stock issues and a disincentive for giving up the original ownership.
This would encourage people to invest in newly started or growing businesses. It would also encourage companies to acquire new capital, thus acting as a disincentive for excessive leverage.
As a bonus, there would be no need to define any ambiguous terms like "angel investor".