I wanted to receive messages from friends while I was offline (because, remember, you had to dial into the internet and tie up a phone line...). I was amazed by the utility of store-and-forward network architectures, but I was surprised that SMTP was the only high level protocol that seemed to use it. Why couldn't something send me my messages when I came back online? It seemed so simple (I think ICQ even supported it)
So I found some Perl libraries that could talk the AIM protocol (later OSCAR) and started hacking. I was able to beg my way into a free shell account on a Linux box and used it to mock up a client with a chat interface. Say hello, and it would give you the options: send a message to a friend, get a fortune, play a game, etc. If you sent a message to a friend, it would wait until the friend was online and relay the message. It also had pre-recorded responses for how I imagined people would talk to it.
I don't know how, but word got out about the bot, and eventually I had dozens of people playing games and getting fortunes, and occasionally using the message-forwarder. It was amazing to me that people liked using this dinky chat bot that I put together for fun, and it inspired me to get into open source development. I think was 16 at the time.