My DS was finished with pre-school for the year, and wanted a big boy buzz cut like Daddy has. I cut my husbands hair every month with a simple buzz cut. He has had this cut for over 5 years now. I think our initial purchase of $20 for a trimmer has paid for itself many times over now.
My oldest son used to have buzz cuts when he was younger, and now sports a "hockey hair" look. I think it is cute on him, and fits his personality. Now that the littlest one looks like a big kid it is kind of sad.
As you can see, I cut his hair outside, due to his hair being so long to begin with. This way I did not have hair all over my bathroom. I used a number 6 so it wasn't to short, but it is still pretty short. Normally I make the top a size longer, but desided to keep it all one length to make it easier. One suggestion is to wash their face before beginging. He had just finished a ring pop, and his face was all sticky and the hair stuck to it instantly.