Hamachi is basically one of the greatest applications ever written.
Among other things, it turns Windows Vista into a viable platform for LAN gamers such as myself. This is like transmuting shower mildew into iridium/steel alloy knives.
Normally mixing different versions of windows on a network is like a dysfunctional and potentially violent family reunion, but Hamachi somehow manages to make all these computers exchange information without trying to kill themselves.
Plus, you can add people to your LAN over the internet (the thing it is actually designed to do). This is great for when your cousin in the next town wants to join your SWAT 4 party.
The only downside to Hamachi is that the fear of it is causing many publishers to drop LAN play entirely. The fear that people might be able to play over the net, without authenticating with their servers, is pushing people in power to take rash actions. So long as it exists they will fear it's potential for evil (piracy hurting sales), so you might as well it for good(old-school, multiplayer gaming with less hassle).
