80 votesSteve commented
Columns would be great. If columns were added, it would also bring a whole level of functionality as utilized by Ecco Pro (a 90's Window's outliner/PIM that still to this day has a strong following).
In Ecco, (which is in my opinion the right way to implement this), a "column" is a representation of a "folder". "Items" (e.g. a line in an outline) can be added to any number of folders, thus when the folder is shown items in the folder are shown. Columns can be added to any "view" (e.g. an outline view that Checkvist currently has), and columns can designate the "field" (e.g. a piece of data such as a date, a checkbox, a word, a selection from an enumerated list, etc.) which ties the item into the folder. It's a real powerful way of approaching an outline, having items be a part of folders, and folders being able to be viewed as columns in a standard outline view.
If you need to check it out in practice to understand how it could be structured/coded, try the newly written 64-bit installer for Ecco Pro: http://www.compusol.org/ecco/
3 votesSteve commented
This would be GREAT!! Mainly, it would be nice to filter farther out than next month, so next _x_ months would give a longer horizon of due dates.