Have an iPad already? If not, here is more incentive to you movie lovers: SnagFilms has just introduced a free app for the device, allowing you to stream 50 of the most popular documentary titles available through the site. And unlike Netflix Watch Instantly, which also works on the iPad, these films don't cost you anything. Some highly recommended titles offered free through the app: 'The Times of Harvey Milk,' 'Jazz on a Summer's Day,' 'Super Size Me,' 'The Future of Food' and 'Dig!'

Also coming soon is the opportunity for Comcast cable subscribers to stream movies and TV shows on their iPads (and other Apple as well as Android devices) via the Xfinity TV app, which currently appears to solely function as a guide and remote control. According to a press release, this new "play now" feature will bring 3,000 hours of On Demand and live programming to the app. Soon there will also be access to social networks for you to share what you're watching with friends.
Hopefully other cable companies will follow suit -- Time Warner Cable has been teasing about something similar -- but for now there are still plenty of ways to watch feature films on the iPad. iTunes, obviously, is one. Netflix, while not free, has plenty of titles to make the cost worth it. And of course there's always YouTube and Hulu. Even Vimeo, which has been a great venue for shorts so far, is getting into longer form content by offering its Plus members the ability to now upload 5GB of video.

There are per-title rental apps like mSpot and set-schedule services like Cinema for iPad, both of which appear to have a very mixed bag as far as user reviews go. Meanwhile, Air Video still seems a good way to stream other video content to your device by way of your PC. There's also a FlixFling app for that.

We're sure to hear about more movie apps and services this week as the CES show in Las Vegas continues. Additional teases coming out of the convention include a Boxee app that will allow its licensed content to be streamed on the iPad. And then there are also the iPad competitors, like the Motorola Xoom, being unveiled that could offer their own alternative and exclusive apps in the future. Either way, the more movies and more ways to watch them, the better.

iPad users: what apps do you use for streaming movies on your device?