I bought a Gator Grip socket from Lowes awhile back and its a pretty handy socket that fits nuts from 1/4" to 3/4". It has these pins in it that allows it to conform to almost anything. This thing is great to carry around instead of a socket set.
Here's a link to thier site if you want to see what one looks like. I'm sure most people have seen these things anyway.
http://www.endeavorproducts.com/