Seeking Watchdog Hardware?

hpavc asks: "I have played with watchdog daemons and hacks on and off for a while. I am wondering if there are any reccomendations out there for which real cards watchdog cards are of the best value. Or as some suggest is it all just a scam. From what I read the mechanisms of the cards differ greatly, both in their monitoring and their response. From simply watching an area of DMA to an embedded device with a os that monitors a large amount of things on the computer hardware and the environment. (tia)"