I've not used it, not even heard of it before two minutes ago – but on being told of it, I wanted to make sure you knew too. This fairly basic-looking tasks app, Lists To Do, is free for today only.
It's usually 69p so it's not like that will destroy your bank balance, but To Do apps are so important that it's worth checking out a lot of them. And a lot of 69p can add up.
So do take a moment to check this one out here.