One of Asana's most powerful features is the ability to have tasks exist in multiple projects at the same time. We discussed a few ways that we use that capability here at Asana, over on the Asana Blog:
http://bit.ly/w0JoUr
If you have some examples of how you've used this, please share them here by posting an answer!
Thanks,
Ryan from the Asana Team
I think it's also worth mentioning that you can assign tasks to multiple people at once as well. This is great when you have something that needs to get done and no strong preference as to who does it. First person who gets to it can knock it out.
On a related note, one thing that I've noticed about Asana that doesn't seem to be documented is that you can assign a task to someone via email by using the URL # of the person (under People in project view). That avoids you having to also include their email address on the email you send.
And it's through that method that you can place the same task in the Inbox of multiple people at the same time.