I tried adding custom links to the SQLFORM.grid and it works great. This functionality can be used to add a custom column indeed, although I feel it isn't best suited to do so... I mean, it can be used like this but than it might be needed to disable those standard links (edit, etc.) there or the design of the view could become really weird. Or am I missing something?
With SQLFORM.grid and custom links, would it be possible to: - add a custom label to this column - change the order of the columns, to move this column to another position within the grid - use this "virtual" column to perhaps sum or otherwise tamper with the existing two real columns? Perhaps such functionality would be better achieved trough computed or virtual fields in the model?

