On a more serious note, if you lock sheldon style (or close to it but using the seat tube instead) you can lean the bike against the crank arm.

Crank arms have a more durable finish and you probably don't care as much about scuffs on them. If you are using a mini U lock, you might be able to get everything tight enough that the bike can't be made to lean on the top tube but with a longer lock, there is alway a chance that someone can knock your bike over into the post...It isn't easy to do (wind won't do it) but somebody squeezing a bike in next to you might knock it over. To combat this, you can always put something in the middle...if you lock with a chain or cable, loop it so that if the bike is knocked into a post, it will land on the covered section of chain.