I've been on a musical mailing list (for Happy Rhodes, called Ecto) since 1991. There was a period back in the mid-90s when several members, including me, were big on gathering together on irc. Sometimes there'd be a few people, sometimes a lot, and at all hours, since fans from all over the world were on the mailing list.
One night a regular named revvie was chatting with 2 others and began to have heart pains. The others were alarmed and got information from him before he passed out. One of them called the police in revvie's city and got paramedics to go to his apartment. They found him unconscious with his head slumped on the keyboard, revived him and took him to the hospital. He recovered, but he almost certainly would have died then if he'd been alone, and not on irc.
I think the irc people really had to work hard to get the paramedics to believe that someone in another *city* was calling in an emergency. This was a few years before the net was common to everybody. I wish I'd been in the channel that night.
revvie (Rod L. Bourland was his name, long live Rod) was a good friend even though I never met him in real life. He was fun to talk to on irc and we had many a long conversation.
A couple of years later he died, of heart failure, sitting at his computer. I often think that's how I'll go. I could think of worse ways. I'm just so glad that Rod had a little bit of extra time given to him because of people on the net.
I'm a member on another forum that had a similar situation and it took place around the same time as that poster. He basically went online and said something along the lines of "this is my last post, I've failed everything in life and no point of living" He went on for about a paragraph and the thread quickly took off with posts ranging from "is this a joke" to people actually hoping it's a joke. The Admin tracked his IP to the city he lives in and posted that he hasn't been on since 15 minutes of posting(but the Admin noted the lag of about 10 mins). Luckily, there were a few people who lived near his city and called the authorities. The ambulance was able to get there in time before anything happened. He came back on the board to thank everyone(and I'm sure he meant everyone as just about every board member on that day posted in that thread) for their support and reconsidered his action.