Artificially burden the CPU

I'm looking for a command line application that will artificially burden the CPU. It needs to be better than just a busy loop. We're testing how the system holds up under heat stress and the CPU needs to generate as much heat as possible.

I've had good luck with:

dd if=/dev/urandom of=/dev/null bs=1024

It keeps a single thread at 100% CPU. Run multiple times to keep more cores busy. Nice it if you want to.

Followed Zoredache's link. The question isn't really what I'm looking for. However, the accepted answer mentioned cpuburn.

*** WARNING ***
This program is designed to heavily load CPU chips. Undercooled, overclocked or otherwise weak systems may fail causing data loss (filesystem corruption) and possibly permanent damage to electronic components. Nor will it catch all flaws.
*** USE AT YOUR OWN RISK ***

With a warning like that it's got to be good.
My one concern is it's a bit old. You'd think an app that used some of the new vector processing instructions could do a better job at heating up the cpu.