: However, unless I
: missed something, the only source they suggested (aside from a hardware RNG)
: that seems available, and unguessable by an intruder, when a Unix is
: fresh-booted, is I/O buffers related to network traffic. I believe my
: solution basically uses that strategy, without requiring me to reach into
: the kernel.

A few more sources are statistics on your filesystems (easily
and quickly obtained) and the output from the "rusage" system
call.  

You can also exec a finger to one or more favorite heavily-used
systems, though this can take several seconds.

cf. the source code to RIPEM on ripem.msu.edu.