I've got two with and one without.

The one without started out brakeless because I couldn't decide which handlebars I wanted to use. While I was switching between drops, moustache, and two different bullhorns, I didn't feel like unwrapping and re-wrapping the bar or with mounting the lever, so I didn't.

Once I settled on the bullhorns, I'd ridden it enough to realize that I'd never really used it much anyway, and didn't miss it. Besides, a nice bullhorn looks ever so much better without a brake lever (although I could see putting a nice little inline lever like the one that Soma or Paul makes, if I had to use a brake).