I still remember Pidgin very well. Back in 2006 (or 2007?), most of my campus friends used YM on Meebo.

I used Pidgin until 2011, I guess. There was Pidgin portable, which was very easy to use on computer labs where you don't have install acess.

Then most people switched to BBM. I worked as a BlackBerry dev at that time, so I followed that path.