First it turns the basic idea of email upside down that's anybody can send mail to anybody's inbox. With Tusulog messages from people you don't know goes to Public Pipe and also you can disable it altogether. BTW, your friends can send to your inbox directly.
Second with email you apply the filter after getting the message. With Tusulog you apply the filter (pipe) before. PG, taking your example literally: You create a TODO Pipe with public_key THEPUBLICKEYOFPGSTODOPIPE. You give this public_key to people you want. They can send message to that pipe in other words they can put a task into your ToDo list. They can do it using Tusulog UI or Tusulog API.
edit: added linebreaks
My 2 cents: I think it will be hard to build traction if all tusulog subscribers have to convince friends and associates to register for a tusulog account. Perhaps one way around it would be to allow registered users to accept and send email from/to non-tusulog accounts, with support for handling non-tusulog accounts with pipes. That way you get to enjoy the features of tusulog, without imposing it on others, and avoid the chicken and egg, first fax/telephone conundrums, etc.
bdfh42: you know it's just like that always. Chicken-and-Egg. Maybe you can open another account to test or add me as friend http://tusulog.com/people/mehmet we can exchange a few.
kaolinite: honestly you should have a few friends over there to really decide you want or not. A reason maybe as a user you've absolute control of your inbox.
A good demo would help - perhaps some legacy support to get things moving?
