Based on what I saw walking away from the Obama rally here the other night...I was in the area but not at the rally; I don't care for crowds...I'd say that the way to get a sign is to go to a rally. There were, at least according to one newspaper estimate, 45,000 people at that rally, and I'd guess that half of them came away with a large sign.

As a matter of contrast, only 1,500 (yes, fifteen hundred) showed up for a McCain rally earlier that day. Of course, you had to get advance tickets for the McCain rally - I really don't know if the pledge to vote for him is still being required to get a ticket or if yard signs were being given away - but only half of the available tickets were given out.   It was a much smaller venue, I'd guess in anticipation of a much smaller crowd.