I have been using
FlightLogg.in' - Online Pilot Logbook for a while now and its completely free. It is pretty decent and has some good functionality. Such as it automatically backs up and sends you a excel email spreadsheet periodically to keep incase the site goes down.
However, I have just moved to MCC Pilot Log as I wanted to be able to update online. The Basic version is free for your PC and you can log on there as much as you like. But I thought for a one time 60 euros it was worth going for the top level and be able sync ipad/android phone and PC to the logbook.