This concerns games, primarily: plus I don't know where else I might place this thread. It allows you to host a LAN server, and for somebody else to join it who isn't on your LAN network, or so to say...
This program I am about to post is *VERY* helpful when it comes to hosting a strictly private server for Warcraft, Starcraft, Diablo, and some other games; even Half-Life & mods.
http://www.hamachi.cc/There is the homepage for this program, it is relatively easy to use: plus it's completely free. If you want a more in-depth explanation as to how it works, read it's Tutorials it offers (I think in the forums there).
Please don't worry about the legality of this program, it is 100% legal, not ripped, and although hated for how it connects networks; it still rocks.