I once posted my idea for a station between Redhill and Reigate, underneath the A25 at Hatchlands Road/Linkfield Corner (some may know this as Reffell's Bridge, but the local spelling of that name varies hugely so I'd hardly want that as a station name!). Given this thread, it may as well get another airing.
This would relieve some of the pressure on Redhill station itself, allowing that existing station to mainly serve the catchment area on the other sides of the town centre and flow a little more freely as an interchange. Hatchlands Road is in the middle of a densely-populated residential area which would mean that it could survive on local and London-based commuter flows, without dedicated parking, though there is a small car park over the road if need be. It would also have a direct interchange onto a couple of bus routes serving the local area, a shopping parade in the immediate vicinity (as well as a leisure centre, two primary schools and both of the marked cycle routes between Redhill and Reigate). It could see a service of around 3tph, and in the Down direction it would be neatly aligned with the end of one of the signal sections.
My idea would be to build the platforms where there are already access platforms for signalling equipment, on the Reigate side of the A25 road bridge, with pedestrian access running on fenced walkways under the bridge (parallel to the tracks), then onto the pavement at the Redhill side of the bridge by two separate means. A ramp already exists behind part of the shopping parade (past the pharmacy) and this could be used for step-free access from the Up platform, and a lift and steps (where the track access steps already are) would allow access to the Down platform.
I suspect with some fiddling, longer platforms than at Reigate could be installed with minimal land grab, thereby allowing a turnback facility if termination of a train wasn't practical at Redhill. Bi-directional running could be implemented up to the crossover on the Reading lines near Redhill itself. A similar distance between stations and emergency crossovers is in use at Coulsdon South, not far away, though that is only used once in a blue moon.
The station could also be promoted as allowing easy access up onto Wray Common and across to the North Downs, as it would be more pleasant than the obvious routes from Reigate, Redhill or Merstham, though there'd be some work to do on pedestrian access arrangements.