Old computer, yeah- Raspberry Pi, not so much. Takes hours to compile node from source, and I've only been able to find one source for ARM node binaries.

And after all that, hubot still ran pretty damn slow. :(

Presumably you'd buy a Rasberry Pi v2 that has arm v7, and can run full/regular Debian with a proper kernel?

https://wiki.debian.org/RaspberryPi

Still, Debian only ships nodejs 0.10 (even Sid) for now -- and I'm not sure what the status is for compiling node 0.12 on armv7 (it apparently has issues on armv6 which the rpi v1 runs).

Fwiw, if you can get by with node 0.10 for hubot (Which I think you can[1]?) -- there shouldn't be any problem:

http://archive.raspbian.org/raspbian/pool/main/n/nodejs/

Unless you need to compile your own nodejs binary for some reason?

[1] https://github.com/github/hubot/blob/master/package.json