Noy much krausen

I've noticed that most of my beers do no develop a krausen while fermenting. I use dry and liquid ale yeast depending on what I brew and I introduce plenty of O2 into the beer before laying it down. Any ideas as to why there's not much krausen? They ferment just fine but I'm jealous of all of the cool krauseny carboy pictures :cross:

I brewed an ESB yesterday and its bubbling away and the initial foamy layer that developed after shaking the hell out of the carboy is gone and the beer is very cloudy and smelling wonderful... where was the krausen?

I've found that now that I am making starters for my liquid yeast, I get a massive krausen that I didn't see before. Maybe pitching rate affects this?