After seeing the CA Communities site, and looking at the content, I am reminded of some of my own history. I've only been with CA for two years.
In 1999, with another developer I built a forum system for a community that went well beyond what we had envisioned. We worked for Userfriendly Media.
Userfriendly.org was a thriving tech community based around an online comic strip. At its peak, discussions for the community reached 12 million page views per month. That translated often into over 100 page views a second on Monday mornings, as our community was usually taking a break at work to read and comment on the content.
It's now largely static top level content, but in 2000, it was a going concern. New content every single day, and a very long list of users. At our peak we had something like 50,000 regular users.
Unlike most other systems before or since, we concentrated our development efforts on performance. This had a surprisingly direct effect on the community. Because it was so fast, and also because of what our default threading view looked like, people often treated it as something more akin to IRC than a traditional threaded discussion board.
Quick witted repartee became one of the modes of conversation. Another mode was direct commentary on the topic of the day, which was often directly related to the comic. Another section of the top level provided comment was news articles from the tech community and our own community managers' posts. The community developed its own etiquette, and created a pretty safe place in what was at the time, the wild wild west of the internet.
Long after we all but shutdown the company, the community continued to play in the space we created. This was partially due to how easy it was to keep the system going. We built lightweight, and it was fast enough that two relatively slow and small machines were able to keep up with 30 million http hits a month, 12 million page views. This meant it was cheap enough to run on a shoestring.
The major takeaway I have is that communities are not a reflection of their creators, they are by far a reflection of their users. So many of the things we did in UF were not a result of direct company involvement, but rather the community itself creating or demanding them.