I use Pocket Informant (http://www.pocketinformant.com/ http://www.pocketinformant.com/). It is kind of GTD-based (though flexible enough to accomodate other wo

I use Pocket Informant (http://www.pocketinformant.com/ http://www.pocketinformant.com/). It is kind of GTD-based (though flexible enough to accomodate other workflows), synchs with Toodledo for tasks and Google Calendar for Calendar, has push notifications. Last time I checked it had a free lite version but after using it for a little while I did not hesitate buying a full version. I used to use (already mentioned) Zenbe lists for TODOs, but since then I migrated all TODOs to Pocket Informant. Zenbe Lists is great but is not really a task management app. I still use Zenbe for nice-to-do things and checklists like 'movies to watch', 'books to read', 'groceries', 'travel packlist' etc.