For BitShares.org/investors, I was in favour of the main page using an updated version of the new BitShares logo surrounded by the most popular BitAssets, superimposed over a dulled background graphic indicative of a decentralised network.
So an updated version of this, using the words 'BitGold' and 'BitUSD' etc.
I would place it over a dulled and lightly blurred background image that is indicative of a 'global, network, decentralised' etc. Some examples of the type of background...
One good image like that that communicates BitShares, BitAssets and that they're part of a decentralised, globally accessible network is the kind of direction I'd take for the main investor image.