In case you've been living on another planet, you've probably heard of Netflix. If you've not tried it, give it a shot. I've used it for about 3 years now, and we love it. No late fees, a long list of movies in the queue, and prepaid mailing envelopes. On average, we watch 2-3 dvd's a week, but if you pushed it, you'd get about 9 in a week. They send 3 at a time, and as you watch them, send them back, and they send you another.
The best part, in my opinion, is the no-late-fee. I've probably put the kids of several Blockbuster managers through Harvard, (okay, through MTA truck driver's academy) but since trying Netflix, I've not paid a dime more than $20 a month, and sometimes had a movie for months (the kids get a wee bit of OCD with some movies).
If you wanna try it, go to Netflix, and use the code Friend63 to get a free (one month, I think) trial.