Online DVD Rental sites compared and reviewed

I've been using the Blockbuster on-line unlimited DVD service for a few months now and can highly recommend it. However, because these services don't lock you into a 12-month contract, you can swap and change at any time (taking advantage of free trials etc). The site below compares most of the UK online DVD services, and is a useful resource if you're new to this type of service.
DVDrr.com