As you might have read (if you checked out the MythTV.org web site) MythTV has a boatload of features. I really only use a few of them, but what I do use, I love.
I use MythVideo to view any videos (tv shows mainly) that I have on my disk.
I use MythWeather (Ann really likes this one) to check the weather before I go to bed each night
I use MythDVD to play DVD’s. What’s really nice is that you can rip a copy of your DVD and keep it on your hard drive.
I would love to use MythTV, but alas, cannot yet get it to play HDTV content (read more later).