For everyone... What was the biggest and most important

[Dravyk]

I'd say it's different things for different people.

Grimm, Mayor ... freehosting.

FM ... click program.

Timon, Spanker, Robin, everyone on AWI ... consoles.

I'd even bet the enthusiastic VOIP users would pick that. And people who live far off and do lot of international stuff would say Skype.

For networking and such ... boards, ICQ.

Overall, to pick one, I'll have to go with Timon's "click programs" answer -- though I'd up that to "affiliate programs" in general ... cause if there weren't money in this, none of us would be here doing this.