Thanks! - this is where I got the 15mm idea
http://www.ehow.com/video_4415604_re...s-bicycle.html
At around 35 seconds into the video the mechanic mentions a 'pedal removal tool' or if you don't remove pedals that often a 15mm wrench can be used. Then I found some nice metal pedals like I wanted - and they say 9/16in so I was confused.
http://www.amazon.com/Park-Tool-PW-3.../dp/B000OZBK32
I guess I'm not interpreting something right? I noticed the tool had a 15mm side and a 9/16 side. I really didn't want to have to buy the tool as I doubt I'll swap pedals very often.