Well, now that it's over, I think the "Yes, We Can" song was the best I saw. Here's a link to a good-quality video:

yeswecan.dipdive.com.

There's another song from the same source, We Are the Ones

Obama used the "Yes, We Can" theme over and over again during the campaign, and it was very effective. As far as I can determine, the song is based on Obama's concession speech given January 9, 2008, after losing the New Hampshire primary. Obama used the "Yes, We Can" theme again in his victory speech last night.

Wikipedia has a good article on "Si, Se Puede" (Yes, We Can), which has been the slogan of the United Farm Workers Union since 1972.

-Joe-