Lately I've had to put NODOWS on hold while I roll out some standard servers, but I've been working on some more ideas for open source appliance builders.
I now have more experience with pfSense, a great embedded platform, as well as python and shell scripting, but the most important thing I think will be the way that os images are distributed. I'm thinking of setting up something with apache, php, perl, python, and mysql. I'm omitting ruby because I just don't know it that well, and none of the applications I'm using are using it.
Under this, it would be great to have either debian or freebsd. I plan to create a "webmin" interface for configuring the basics, as you find in pfSense, m0n0wall, freenas, and askozia, though I plan to use a different framework.
My plan is to have the OS be installable onto solid state hardware in read only mode, using unionfs to provide runtime writes. For the application files and database storage, the os will have the ability to initialize, mount, and access various media, including regular old hard drives, CDRs, and iSCSI devices.
That's the plan anyway! :-)