Good ARM development board for bare-metal development
What are you going to do with it? Relative to your requirements the BeagleBoard and BeagleBone are a couple orders of magnitude of overkill, although the Bone is an amazing value for its power and hackability. I'm not sure why you say it fails requirement 4, it has all those things except perhaps the nice documentation. The Beagles seem to be pitched as linux platforms so I don't know if you'll be completely on your own if you want to bootstrap it yourself; unlike with an MCU you may not have a bunch of C libraries for working directly with the hardware and peripherals.

Have you considered an ARM Cortex M3 or M4 microcontroller kit? STMicro has a $20 discovery kit for their new Cortex M4 micros. 192KB RAM, 1MB flash, JTAG, USB, and a pretty awesome array of peripherals. These are targeted towards bare-metal development so you will just get some C libraries that let you configure the hardware and you provide a main function and interrupt service routines. It doesn't have networking but at that price point, unless you are designing something where that's a make or break requirement it's an amazing value for learning and prototyping. I have one in the mail now so I can't give a first-hand account but I have developed on other Cortex MCUs and really like them.

If you do require networking, I have used TI's Stellaris LM3S6965 Ethernet Evaluation Kits and they are great, the docs and libraries are pretty good (I've hit a few stumbling blocks figuring things out but overall a good experience). I've even used lwIP and UIP to build a device with a (very, very, very) simple web server. I'm a little reluctant to recommend the full kits over the BeagleBone though because they are around $70 and vastly less powerful than the Bone, but it all depends on what you want to build or learn.