I use CinemaParadiso. I thought Lovefilm was the only game in town. But I searched Google for 'UK DVD rental' and found CinemaParadiso. I signed up. That was 6 months ago. Now I watch about 3 disks a week and love the variety.

Just to clarify: I was a big fan of Lovefilm with 4 disks at once, but Amazon shut it down.

Just a note: CinemaParadiso has been a private company since 2003 so basically, it is unlikely to be shut down like Lovefilm. This means it will likely be around another 20 years.

Edit: CP changed to CinemaParadiso