WWIV (World War Four) bulletin board software had a networked component called WWIVnet, run by the author of WWIV, Wayne Bell. In the early 1990's, controversy erupted and a group split into a secondary, alternative network called WWIVlink. A lot of bad blood was brought up between proponents of the two semi-competing networks (it was possible to be on both) and it stands as an example of how a minor disagreement online could get completely out of hand.
Additional Notes:  
An excellent posting from Don Brown in COMP.BBS.TBBS gives a nice overview of WWIV and WWIVnet:

"WWIV (World War Four) is a BBS that was written by Wayne Bell in the early 80's as a high school programing project. He shared the software with 25 friends and soon the need arose to share messages from one board with all the rest. WWIVnet was born from this need. Originally programed in basic, more power was needed and WWIV was redone in Pascal and then moved to "C". In all its forms WWIV's source code has always be available to registered owners. This encuraged sysops to develop new features for WWIV and these ideas were released as "Mods" that others could add to their own copies. There are many professional "C" programmers that got their start poring over WWIV source code. WWIVnet was also available to those that registered. In its hayday there were over 1500 BBS's connected through this world wide network. Yes, it was much smaller than FIDOnet, but the sysops were very involved and dedicated to BBSing, as a result a small core of systems are still running and more importantly still developing WWIV...."

In the proposal for COMP.BBS.WWIV, there is this description of the whole situation:

"At one point, WWIVnet was the world's largest proprietary BBS network. That can no longer be considered the case, as systems running Waffle and VBBS are now part of the network. WWIV is coming into its own as a BBS software. For quite some time, continued development of the software floundered as author Wayne Bell tried to juggle both development and administration functions for the software. He turned the administrative chores over to another sysop about 8 months ago, and development efforts have come along rather nicely. WWIV-based networking had previously consisted of the following: WWIVnet (run by Wayne Bell and based in California), WWIVlink (based in Illinois) and IceNET (based in New York). One of the more recent additions to the networking software was the ability to create multiple networks. This has led to a million or so little RadDudeNets (as so named by one WWIVnet sysop, as WWIV does appeal to a lot of teenagers and pre-teens) popping up all over the place. The three aforementioned networks still stand out today as the only truly significant national WWIV-based networks, though. In years past, WWIVnet has had some gating (all external and often very klunky) to Fidonet and Usenet. Usenet gating is now accomplished more easily by the WWCP gateware, but that runs with Waffle and connects to WWIV."

WWIVnet definitely dwarfed WWIVlink.

modemwld.txt (12K) The Modem World, by Charles P. Hobbs of the Blue Cafe (Mentions WWIVnet)
2002-01-27.dbrown.txt (4.1K) Usenet Posting to COMP.BBS.TBBS by Don Brown in 2002 describing aspects of WWIVnet and WWIV history.
comp.bbs.wwiv.txt (50K) Proposal for the start of several groups, including COMP.BBS.WWIV, by Sean Patrick Ryan (March 29, 1993)