What better way to kill 1 hour and 20 minutes on a long flight or road trip than by taking in a movie on the go? The trouble is, downloading movies at $10-$15 a pop can get expensive, buying DVDs and ripping them to a portable device takes time, and ripping rented DVDs is just plain illegal. Fortunately, there are a few services and devices that allow you to take low-cost rental downloads on the go.

The most well-known download rental service is Apple's iTunes store, which rents movies at around $2.99-$4.99 that can be played on most recent generations of iPods (Classic, Touch, and generation 3 and 4 iPod Nanos), as well as your computer or Apple TV. You get up to 30 days to begin watching your rented movie, and 24 hours to finish it once it's begun.

For celluloid connoisseurs who find the 3.5-inch screen of Apple's iPod Touch a little cramped for mobile movie marathons, the Archos line of Wi-Fi-connected portable video players offer more accommodating screens.

With Archos' partnership with Cinema Now, devices like the Archos 5, 605 WiFi, and the gargantuan 705 WiFi, can connect directly to Cinema Now's online store, and download movie rentals priced between $2.99-$3.99. Viewing restrictions on rented movies from Cinema Now are similar to Apple's, giving you 24 hours to finish a movie once you've begun watching it.