On the same basis as the tasks comments, I think it would be great to be able to edit a detailed description of each tasks.
A detailed description is really important if several people can create tasks. It provide a clearer insight of the perimeters of the tasks, may enumerate a number of subtasks, providers, hyperlinks, etc...
Of course, one can create a text column containing this description, but these can't be richly formatted and to my mind really overload the lines. Furthermore, they are not required all the time on display (just as the comments), as task names often become explicit enough after a fashion.
What I would love to have is a button beside the Comment one, that, when clicked pops up a richly formatted text, could be edited by anyone.
Thanks for your awesome work!