Trial offer: Receive three days of access free when you create an account at Cinema Now. Rental fee: $9.95 per month for streaming access to thousands of adult titles. Relative size of selection: 2 of 4 stars. Credit cards accepted: Visa, Mastercard, Discover, American Express. Sales tax: Not stated. Customer service: Via site. Open to: U.S. residents.

Best Adult VOD Site?: The most popular VOD service in our guide is Hot Movies, which has tens of thousands of adult titles. You can buy access by the minute (at 8 cents and up) or purchase unlimited viewing of any individual title for two, seven or 30 days. Our most popular flat-rate site is Video Box, which charges $9.95 per month for unlimited downloads from its library of more than 3,000 movies.

Prefer to Rent DVDs?: If you prefer to rent DVDs rather than download movies, compare online services at our Adult DVD Rental Guide. Most charge $10 to $30 per month to have one to three adult DVDs out at a time, with no late fees or return dates. A few rent individual DVDs for $3 to $5 each per week. A credit card is required to join any DVD rental service.

Discount Adult DVDs: If you're looking for bargains and selection, we suggest Movies by Mail, which offers new customers a free movie when you pay $4.95 shipping, as well as discount codes (see site), XRent DVD, which sells ex-rental titles from $4.50 each or Overstock DVD and Adult DVD Empire, each of which have many clearance titles and offer free shipping on every order.

Video Gold Adult DVD Club: Choose two adult DVDs for $5.95 each plus shipping when you join the Video Gold Adult DVD Club from Adam & Eve. You'll also be able to choose a third adult DVD free. As a member, you must purchase two more DVDs at regular club prices within a year. Or purchase a fourth DVD when you sign up for $19.95 and buy just one additional DVD within a year. Open to: Residents of the U.S. and Canada.

Search for Sex Books: Browse the list of sex book bestsellers at Amazon.com, including The Adult Video News Guide to the 500 Greatest Adult Videos of All Time.