With perl 5.8's new iThreads you could easily write up a quick multi-threaded script that could use X amount of threads, each one pinging a machine. For more info, check out the perlthrtut.

However, this is obviously for tracking servers/machines remotely to make sure they are still alive, in which case, this wheel has been invented many times before, and much better than it could be written by a single person in any usable time frame.

Windows: What's Up Gold works pretty well, very graphical and boss-friendly (ooo, pictures!).

*nix: There are several, I have used both NOCOL and Big Brother. Choose whichever one works best for your needs.