Is it possible to share my todolist for a certain project with my boss without him being required to login?
He doesn't use the service, and I don't want to make him sign up.
Unfortunately, this is not possible right now. Have you tried printing you to do list as a PDF and sending it in an email to your boss? If he is not using the service, what did you have in mind so your boss can check your shared to do list?
Feel free to add this on the votebox https://todoist.com/Vote/ though.
Just a webpage with read-only display.