Hi, My wife and I would like to use this program seperately for work, but also have a shared personal to-do list. How do we do this?
Unfortunately, sharing is not available on Todoist right now, but we may consider adding it in the future and you're welcome to add your vote for this request in our Votebox: http://todoist.com/Vote/showProposal/204/
For now, we have another app created for team-based project management: https://wedoist.com and you're welcome to try it out.
Alternatively, you could create a new Todoist account and simply share the password to it and have shared projects within it.
Does Wedoist integrate with Thunderbird?
Unfortunately, there are no plugins for Wedoist yet, but we may consider adding them in the future. You're welcome to add a request to the Wedoist Votebox: https://wedoist.com/Vote/
how about taking this offline, now that it's possible to share tasks?
You can use Todoist offline as you always could, but please note that updates from shared projects will not arrive in this mode.