Yep, for security reasons, hardware is definitly the way to go. The "Remote" link in my last post points to a hardware based bord that has a graphical remote control java applet built into it, and it has had no security holes that I am aware of. Dell also offers a similar hardware based card, though I have never worked with them. From a quick glance, it looks like they require extra software to be ran somewhere to access them, and no PDA access exists for them.

If that much remote control is not needed, the BIOS on most of the servers I work with supports a modem or serial link, and the callback feature bonzi talks about. Though it's text mode only, so most would be out of luck for routine maintaince under GUI based OS's. (It's also the reason newer servers in the pipeline have an integrated version of the above discussed card.)