Kali is a multiplayer gaming service for DOS and Windows. It was written in 1995 by Jay Cotton and Scott Coleman.
Kali works by emulating an IPX network over a TCP/IP connection. The service bears a great resemblance to Kahn, but was much larger at its peak than Kahn ever was. This was mostly due to the earlier release of Kali compared to Kahn. At its peak, Kali was the largest multiplayer service in the world, offering service for basically every game in existence and hundreds of servers to play on. Kahn offered a faster connection (in general) but failed to surpass Kali due to Kali's larger playerbase (in other words, Kahn had fewer players because Kali had more players, if you follow me), larger coverage in the gaming media, and slightly easier to use software.
Currently, Kali is free to use. During its heyday, however, Kali cost a one-time fee of $20, which was a very good deal during that age of pay-per-hour multiplayer services (remember TEN? Mplayer? HEAT.net?). I am fuzzy on the details, but the company behind Kali was either bought out or went bankrupt. The service is now run without a real possibility of a new version by its co-creator Jay Cotton. In this respect, Kali is very much like Kahn, with the major difference that Kali actually works on modern versions of Windows.
The game Warcraft II (and possibly others) included a copy of Kali on the game CD. Indeed, Blizzard even released a special version of the Warcraft 2 executable (WAR2KALI.EXE) which optimized the game for use over Kali. This is actually very odd, as recently Blizzard was criticized for shutting down a project called Bnetd, essentially a third-party implementation of Blizzard's Battle.net service, on the nominal grounds that it allowed players to play pirated versions of Blizzard's software online, bypassing Blizzard's CD-key security system. Kali, of course, would allow this sort of thing just as easily. And Blizzard was involved with them in the past, so it's not like they're ignorant of its existence. Go figure.
The Kali website can be found at http://www.kali.net.
Time passes, things change...
Kali is back. Jay Cotton has reacquired the rights to the Kali name and source, and has relaunched the service, both in its old capacity as an IPX wrapper, but also as a more modern TCP/IP matchmaking service (kind of like GameSpy, only without those aspects of GameSpy that are so completely annoying). It is still free to download and use, but a one-time $20 fee is required to gain access to certain important features (such as the ability to host a game).
As an added bonus, registration keys from Kali's first phase of life are still valid on the relaunched service (they meant it when they said "lifetime registration"), so its users from days past can jump right in and play, assuming they still have their registration number.
The one-time king of multiplayer gaming is making a bid for the crown again. Judging by the stability, usability, and elegance of the GameSpy client, the only thing stopping Kali is GameSpy's sheer size. Piece of cake.