] PhreakNIC has had between 300-400 attendees per year for the
] last three years. I think you can remove the "possibly"
] qualifier before "even smaller."

I'd really be interested in the attendee rate at the Interz0nes. Rockit and Johhny are rather biased sources. Its hard to gauge number of people at these things, because not everyone shows up to all the talks, and some people pay for the con and only come to one or two events. I only go to certain talks, and never really hang out with the gamers or the Rootwars or the Hacking 101 rooms. And a lot of 101ers never come to the other talks. Here are my estimates for the Interz0nes

1: ~125 +-10
2: ~275 +-50
3: ~250 +-25

Interz0ne 3 felt like it had less people than IZ2, (of course, any observations I can make about IZ2 are probably wrong as I had a lot of shit to handle!)

Other cons I've been too:

Hope: ~Too many
Phreaknic 7, 8: 300+ sounds about right
Toorcon 2004: 500+

Con attendence