After hearing some good reviews from guys at work, I snagged a 2TB Buffalo Linkstation NAS today:
Buffalo Technology - Products - LinkStation Pro Duo
First impressions: I really like it. I'm running it RAID1, so it's 1TB of usable mirrored storage. One of the key things that I like about it is that it has an auto power on state. You run an agent on the machines that you want to access it, and the drive sleeps until it gets a wake-up ping from a machine running the agent. That way, it doesn't need to stay on all the time like most of the NAS's I've used in the past.
It came with some backup software that I won't use on my main machine (I'll just use a bash script to drop stamped tarballs on it) but on my media server and my laptop it's pretty convenient. The software that it comes with is a full licensed version of Memeo, and it has a nice interface for doing incrementals once you have a basline backup in place. It's also gigabit, fast as hell, almost entirely silent even with the fans on, and only has two tiny, very dim LED's on the front panel to indicate that it's even on.
I've no idea what brand the drives inside are, but I'm assuming they're something like rebranded WD's. Either way I can't even hear it swapping next to me and I'm copying shit to it right now from 4 different machines.
All in all, for just over $300 with the service plan, I'm pretty happy with it. Web interface is intuitive, the GUI is awesome, it integrates really well with Windows and the discovery agent for finding the drive on the network is almost immediate, which is pretty badass alone.