As good as the Apple TV 2.0 is, it's still pretty limited on what sort of videos it can stream from a networked computer--if it hasn't been imported into iTunes, you're pretty much out of luck. If you're looking for something with more file format flexibility--and the simplicity of drag-and-drop operation--the LaCie LaCinema Premier may be just the ticket.
On one hand, it's a standard USB 2.0 external hard drive, available in beefy 500GB ($250), 750GB ($350), and 1TB ($500) capacities. But on the other hand, unlike standard backup drives the LaCinema Premier has a full set of AV outputs (composite, S-Video, and component video--but no HDMI--analog stereo, optical and coaxial surround-capable digital jacks). The idea is that you load the drive with all of your digital movies, music, and photos (via a USB connection from a Mac or Windows PC), and then connect it to your TV. You can then use the included remote control to select which videos, songs, or photos you would like to enjoy via an onscreen interface.
Though the lack of DivX compatibility is notable, the LaCinema Premier looks to support a reasonable variety of file formats, including MPEG-1, MPEG-2, MPEG-4, and--rippers take note--the ISO, IFO, and VOB files of DVDs. (Repeat after me: you're only legally allowed to rip DVDs that aren't copy-protected--which pretty much eliminates any Hollywood release.) The spec sheet also mentions "1080i upscaling." So while it's always a crapshoot to judge products from afar (which is to say: we haven't reviewed this LaCie drive, or even seen it in person), the LaCinema Premier may well be a "just right" sneakernet alternative to the too-small SanDisk Sansa TakeTV ($150) and the way-too-expensive Kaleidescape movie server ($20,000)--assuming the network-enabled Apple TV or Xbox 360 doesn't already handle those needs for you.
One final note to LaCie: In addition to adding that missing DivX support, you might also want to throw in an extra power adapter--one to leave at the computer (when you're loading up the drive with content), and one to leave by the TV (when you're enjoying it on the big screen).