Please add “Task” account type where you can add a wunderlist.com account. Then you could point your tasks per mail account at your wunderlist account (support pointing specific email accounts at specific lists within wunderlist like you do with google calendars). That way I can:
a) see my wunderslist tasks on my agenda when they have a due date.
b) create tasks on my wunderlist from an email message
c) view and edit all wunderlist tasks from the tasks panel.
There is a great API provided by wunderlist for this and would be a really great feature to have. I can live without it, but it would be one of those “icing on the cake” features to have.
Honestly if you had a way to build an extension to add this feature I would be interested in developing it, however you do not, so as a side request maybe a feature to allow 3rd party developers to add features like this for you would be something to consider in a future version.