It would be really good to put all my todo lists in one place. I have a loooong list of todo items for threads, a bunch for Mambo OS, a very big bunch for my site and probably more lists as well... I haven't even looked at the threads todo-list in ages, it would be good to have them all in one place. And the ability to let users see some of the things needing to be done is imperative, so that they get guilty and hopefully help out. =]
I'm thinking of having a "Personal" bit in each entry as well, so that only the user adding it can see it unless it is also public. That way, every user could get their own todo list as well if you want. =] But the main thing it would be used for (by me) is to add some of my personal things that I want done, it would be good to have them integrated in the list as well, but I don't necessarily need other admins/mods to see them.