OK, let me jump in with a non-free product: Skydemon.
It does a lot more than just a moving map. It helps with Weight and Balance, Fuel Planning, Range calculation related to wind, gets the weather information for you, keeps it updated as long as you are in wifi contact, gets the NOTAMs for you and shows them graphically on the map if possible, gets the related AIP airport and approach charts, both VFR and IFR, keeps a list of most frequencies you may have to contact. It will make a flight plan out of your rubberbanded flight planning and send it to the authorities (VFR only). It will import IFR flight plans from Rocketroute and Autorouter.
During flight it will warn you of controlled airspace, frequency to contact, advise you of obstructions, advise you of other traffic if FLARM equipped. By helping you with the navigation you have more time to look outside for traffic.
I could go on for a few more pages.
But: it is not free, it will cost you about the equivalent of 4 litres of Avgas per month. These four litres can easily be recovered by easier and better navigation, better planning and knowing where cheaper fuel can be uplifted. So, it reality, it is not free, it pays to use it.