Usenet with compulsive replies -> IRC
Let’s invent IRC! IRC is great! IRC is real time!
Instant Messenger -> Instant Messenger with multiple people -> IRC
Blog -> Blog with compulsive replies to comments -> IRC
Mail -> Gmail with chat -> Gmail with flash chat allowing multiple people -> IRC
Twitter -> Twitter with compulsive @reply -> IRC
FriendFeed -> IRC (with images)
Facebook chat -> Facebook with FriendFeed -> IRC