Like Excel: Forms with Option Buttons, Option Groups, Drop down boxes, Combo Boxes, etc.
They should also render in TM1 web. This would come in very handy for error trapping and showing a message box with some sort of confirmation/warning.
Clicking ok on a form could pass the choices made as paramters back to the originating TI process or to another TI process.
You could even log the user and the choices made for a full audit trail.