OK, I just did a survey of all the new commands in busybox versus what's provided by the one on the Chumby... obviously, some of these aren't included because they're not useful, but here's the list I made up of the ones that would be nice to have around:
ar, bzip2, cal, chattr, cksum, comm, cpio, dc, fold, ftpd, ftpget, ftpput, hd, hexdump, install, lzmacat, lzop, lzopcat, man, microcom, mkdosfs, mkfs.vfat, mkpasswd, mktemp, nohup, od, passwd, patch, pgrep, pipe_progress, pkill, popmaildir, printenv, printf, pscan, readlink, realpath, resize, rx, sha256sum, sha512sum, split, stty, su, sulogin, sum, sysctl, tac, telnet, tftp, timeout, tty, ttysize, uncompress, unexpand, unlzma, unlzop, volname
Good news on the root password... I'm teaching a class on Chumby hacking in February, and wanted to show people how to set their own password as one of the first things to keep students from defacing each others devices.