I know all of those examples and plenty more. I'm not one of the rubes you're trying to fool on your site. None of them are free.

The electric bill option is one of my favorites to see recommended. Have you ever actually looked at what they do to your rates? You're better off paying the (relatively exorbitant) rates to just buy points direct from the program.

Booking hotels through a portal has costs related to alternate points or cash-back earning. So so the shopping portals. The time required for the surveys is far in excess of the occasional paltry sum of points received.

None of them are free.