I have a milk crate up front, between the handlebars. It's not very aerodynamic but it's handy to put things in. Now when I am on a trip I pull a canoe on a trailer with most of the load in it, and just a few things up front with nothing on the rear rack. I find that having some load on the front wheel makes the bike feel more solidly on the road, and when I don't have anything up front it feels kind of light and bouncy. It's probably all just in my head, but that's what I've thought I noticed.
Zach