I've gotten a couple of emails from people whom (I presume) got an AppleTV for the holidays.
First… congrats. The AppleTV is a great little system. We've been enjoying ours quite a bit since last April.
Second… here's some tools that I use to help manage tv shows, movies, music, etc on the Apple TV.
One thing the AppleTV is missing, IMO, is a native DVD player. I understand why it doesn't have one (so that you will rent/buy from the iTunes store instead), but… you've got all these DVDs and you want to watch 'em. So… you need an encoder.
Handbrake – A great free, open-source app can rip & encode DVDs directly to AppleTV formats. Works on Mac, Windows, and Linux. Don't go and buy a program to do this, because Handbrake is better than anything you can pay for. Seriously. Prior to Handbrake, I was a big fan of VisualHub, but that is no longer being supported. You can also use Handbrake to convert movie files from any format to AppleTV – for those of you who troll BitTorrents, etc.
If you buy or rent movies from the iTunes store, you'll love seeing the movie poster, cast, plot info, etc. But if you're encoding your own video sources, none of the information will be included with your file. That sucks, but here's a fix.
MetaX – A great free meta tag application for Mac OSX Leopard and Tiger. Drag & drop your encoded file (right after you use Handbrake) and it will search user-contributed information, TagChimp, IMDB, and Amazon.com to fill in the blanks, such as movie poster, run-time, genre, etc. This is one of my favorite tools. Once I run a movie through MetaX, it's ready to drag & drop to my iTunes.
iTunes is a decent content manager, but it has it's quirks. Become the master of your domain by using scripts to better organize your media library. Enter Doug's Scripts for Mac OSX.
Set Video of Kind – iTunes has a bad habit of importing *all* videos as "Movies". That's not good at all. Set Video of Kind allows you to specify Movie or TV Show, and easily modify show name, season number, and episode Number for one or multiple videos. This comes in *really* handy when you just imported the entire season of Lost!
C'mon… ya gotta tinker with it!
iPhone/iPod Touch Remote – Control your Apple TV from your phone/ipod!
Hard Drive Upgrades – Wanna add more space? Wanna void your warranty? Go for it!
There are a lot of advanced tools, hacks, and add-ons that are popular for the AppleTV. I've played with them, but I really enjoy the core functionality as much as the hacks.
Shoot me an email/twitter if you have questions or suggestions for me to try!