Frankly, the only thing I can think of that McCain is good for is that he adds another "R" to the column, helping to take the Senate away from the Dems, and helping to give people like Jim DeMint extra clout by being in the majority party.
But even then, this only helps us if the GOP gets a large enough majority that a McCain switch to the Dems wouldn't negate it. And that is EXTREMELY unlikely to happen, at least in this cycle.
Just watched the debates. McCain looked like a weak, old, lying, fool. JD took him apart. McCain denounced earmarks repeatedly and then used 3 of his responses to talk about all the pork he’s brought to AZ. What an idiot. Go JD!