Joel Stein discusses ways that humorists can get some jokes out of Barack Obama. Obviously, based on what Stein comes up with, the options are pretty feeble. But don't worry, my fellow comedy writers. Before long, Senator Obama will say or do something, or we'll find out something about it that will yield a gusher. There was a time when it would have been tough to write something funny about Larry Craig. Then suddenly and without warning, it became very easy…