www.aircraftbooking.co.uk - Aircraft Booking System
Ok it costs each member in our group 14p a week but it has stacks of other little things like reminding pilots when their medicals/ratings/ etc are due (and sends all this to me as administrator).
Allows members to update their details, message each other and send group messages.
Also allows a 'first dibs' on a booked slot if it becomes free but most of all instant problem solving by email from the owner.
Worth £50pa of anyone's money.
'Free' is not always best.
Cusco