My two computers both are by now Linux (Fedora and eee-Xandros), and I am doing more or less OK with them, even though my Linux knowledge is still very limited.
However, I moved from Mac to Linux and am still trying to get some of the goodies I liked on the Mac. Thus, I will describe the feature of the Mac, which I am looking for in the hope that somebody has easy instructions for doing that with the Linux computers:
Whenever I had trouble with a mac, I hooked it up via fire wire to a second mac, and started the troubled mac holding down the 't' key. This way the troubled mac would show up like an external hard drive on the other mac (provided the hard disk was still sort of ok).
So here are the specific questions:
1) Can I hook up one Linux machine to another similar to the macs?
2) If question 1 is a yes, then how do I do that?
3) If question 1 is a yes, then can I connect computers with different linux distributions?
4) I know of course that my Linux computers have no fire wire, but I understand that USB2 is pretty much the same thing?

Thanks for any help!

Well, as far as I understand, you could do that even when OS was unbootable. That pretty much answers your question - no, Macs have it in firmware (something was handling it and it was not inside OS.)

Never had a problem with Mac I couldn't fix booting to command prompt. Anyway, in Linux you can boot up using a LiveCD. Then you can use disk utilities to fix what can be fixed and serve broken installation/HDD over NFS to rescue what can be rescued.