Sarah Palin adds an awful lot to John McCain's ticket. For example, she adds an ongoing scandal over her firing the Alaska Public Safety Commissioner because he wouldn't fire the ex-husband of her sister (who was embroiled in an ongoing, nasty divorce and custody battle with said ex-husband, an Alaskan State Trooper). As mayor of Wasilla, AK, she fired the police chief for having supported her opponent in the mayoral election. While running for governor, she supported the infamous "Bridge to Nowhere" in Ketchikan, Alaska, and Alaska is still building the access road to the (empty) bridge site. She supports teaching creationism in public schools.
On a lighter note, she adds three more houses to the ticket (to go along with McCain's "I can't count that high" number). And, of course, she adds eye candy; after all, former POW McCain spent five and half years not having a running mate to ogle: