my roommate uses netflix and he loves it
http://www.netflix.com
You get a plan where you can have 3 dvds at a time, you keep them as long as you want, and when youre done, you send it back (the envelopes are stamped so its easy to send back) and when you send it back they send you a new one thats on your list.
they have different plans where you can watch 3 at a time, 4 at a time, etc.
they dont have any porn tho