I’ve been using the Zip.Ca service for the last week. For $25/month, you get unlimited DVD rentals, mailed to you. Each DVD comes in a small tyvek envelope, with a stamped return envelope. To choose the DVD’s you want, you go to their website, and pick from the (very) large selection they have. When the movies are in, they send them to you. To ensure that you’ve always got a movie to watch, they recommend you have 20 on your ZIP list at all times.
Turnaround time is very fast — it takes no more than 3 or 4 days to get a new movie when you send one back. Since you can have up to 4 rented at any time, you’ve always got something to watch.
I’m pretty impressed!