We are using
AeroPlus: Home 
It's a great product and it has a free iPhone app to make bookings and register flights. It's also a booking and finance system in one package. Also a good place to store documents (POH) and many other options like giving your engineer a log in to live view your technical problems if they occur and someone left a note in the system. You can try it 30 days for free.
Costs €0.65 (£ 0.54) per completed flight if you keep using it.
It is a huge step up coming from aircraftclubs.com for us.