I just realized the other day that 2013 is the 20th anniversary of the online LEGO community! Back in January of 1993, the alt.toys.lego newsgroup (ATL) was established. If memory serves, it was created along with a smattering of other brand-specific toys. To my knowledge, this represents the first time that a dedicated area on the public internet was established for discussion of LEGO!
Towards the end of 1993, people realized that the "alt" hierarchy of usenet wasn't very well propagated (many dial-up ISP's didn't subscribe to it), and the suggestion was made that many groups under "alt" be migrated to "rec". Thus, in early 1994, rec.toys.lego (RTL) began, with a much wider distribution. ATL continued to exist (to avoid breaking things), but it mostly was left abandoned.
As the years went on, discussion traffic increased on RTL, and it became increasingly busy. Many auctions and sales were held there (this was before eBay was popular or even available!), with frequent manual posts of auction updates, making the newsgroup difficult to read for those uninterested in the marketplace.
In September of 1998, a solution was launched: LUGNET. It was created on a hierarchy of newsgroups solely dedicated to LEGO, with separate areas for marketplace, building, CAD, and other areas. Additionally, it hosted a way to post using "the web" and via email (a pretty novel idea back then!). Very quickly, LUGNET became the central hub of the community.
Around the same time, local LEGO clubs started forming, as the population of AFOLs online started exploding (since internet access was becoming increasingly available). Soon, people were able to meet a variety of others in their local areas, providing enough AFOLs to actually form groups.
LEGO itself reached out publicly to hobbyists in late 1999, with the foundation of LEGO Direct-- a move that would eventually steer the course of AFOL-targeted offerings and programs like the Modular Town buildings, the LEGO Ambassador program, and LUGBULK. For the first time (albeit VERY slowly at the time!), LEGO began having a two-way conversation with hobbyists.
In 2000, the first LEGO convention for hobbyists was held: BrickFest, in Washington DC. About 60 AFOLs attended-- peanuts by today's standards-- but also a very close-knit group considering the size and communication options of the time.
Over the next few years, the community began to expand and become increasingly diverse. Many websites with communities started appearing, and fan-held LEGO conventions are now common to many areas around the world.
Happy 20 years, LEGO community!