Since after all one has to develop economical part over tau, using tau's unique features, we're going to do it as Agoras. And we do need to distribute the coins somehow, hence the presale.
Can you explain more about this? What can I do, in terms of interfacing with Tau, with Agoras? Is it just another cryptocurrency that is just built using Tau, or does it have some special status or feature within Tau Chain? Why would anyone want to own Agoras over another cryptocurrency within Tau, or outside of Tau for that matter?
Agoras is indeed "just another app" over tau. This is important to bear in mind. Everyone can create more currencies over tau, and tau doesn't have a coin as for itself.
But Agoras is of course far beyond a cryptocurrency. It will have markets for trading code for money in a totally secure and trustless way (as in Code and Money blogpost), allow renting computational power with or without verification of execution, renting professionals in video conference and micropayments, smart contracts, pay-for-proof wheter it's math homework or a program to write, decentralized intelligent search engine, and even more.