TomatoUSB

Ugh, my build machine (Ubuntu 10.10 on VMware) keeps bombing out when compiling, or cleaning the source tree. Ugh.
Anyways, I'd like to see an IPv6 + USB build for the 4 MB flash routers. I'm running one right now on my 520GU, using the config

"make a MIPS32=r1 V1=9055pre V2="USB-IPV6" NO_CIFS=y NO_SSH=y NO_ZEBRA=y NO_SAMBA=y SLIM=y IPV6SUPP=y"

"make clean" doesn't always catch everything, but running

git clean -fdxq && git reset --hard

What size are those builds?

3.77 MiB.
That's a hell of a tight fit.