In Thoughtboxes you work with Trains of thought. If I got it right, those implement the Areas/Roles of responsibilities part of GTD. Each Train of thought contains Boxes. A Box is like a project, or list and it contains your thoughts (or tasks).
I have to admit, I loved the user interface as much as I enjoyed those refreshing metaphors for the old dull project management words. There are cute boxes and small smiling faces and bright colours in a clear display.
Thoughts can be moved around easily, to change order or to be transferred to another box and can be starred to stand out from the others.
Trains of thought can be also shared with other users, a feature for premium users which I did not test.
While Thoughtboxes is an incredibly well designed and super fun application, it has only a really basic set of functions. I truly wish the developers will add some more functions in the future and it will definitely stand out from the competition.
Free users can have up to three Train of thoughts while premium users ($3/month) get unlimited ones and sharing/collaboration features.