Making music and photos available to Apple TV I have a double story house with the modem upstairs and an Apple TV downstairs. I also have a USB hard drive with an iTunes library and iPhoto library on it. At the moment every time I want to use the libraries I have to plug my USB drive into my MacBook.

I've recently discovered that my modem has a USB port on it, and I can plug my USB hard drive into that. Can I plug my hard drive into that port and make the libraries accessible to both my MacBook and Apple TV?

If possible I don't want to have to keep my MacBook turned on all the time. I.e., it would be nice to just have the USB hard drive plugged into the modem and access my library on the Apple TV without my MacBook being turned on.

In researching this answer I've read a lot about Apple's AirPort Extreme and how it can do something like that. But unless that's my only option I would rather not spend an extra $200 if I don't have to.
This is similar to another recent question: Is Apple TV intelligent enough to stream directly from a NAS?

As @tubedogg says, you need iTunes running on a Mac/PC in your network to share local files.  You can only remove this requirement if you buy/stream everything from the iTunes store.

Unless you hack your ATV.

You can run something like PlexConnect on it to stream content from a local Plex server, but again you need a Mac/PC running a Plex server, so it's not that different than requiring a Mac/PC running iTunes.

I think there might be an XBMC hack (for ATV2 only) that will allow you to stream from a NAS/UPnP device, which might work with your modem's USB port, but I doubt it will work from the AE's USB port.  The AE's USB port is best used for a Time Machine drive, which is a great backup strategy, but off-topic.

So, if you haven't bought everything from the iTunes Store (or haven't used iTunes Match to make a copy of all your music available to you from the "cloud"), you do need to keep a Mac/PC running iTunes to access your personal content, regardless of where your USB drive is plugged into.