I'm going to skip over the Veepstakes discussions, which are largely moot since Obama will make his choice for this office in good time and for the good of the nation.
I also take Hillary Clinton and her supporters at their word for their pledged support to Obama and the Democratic party. I believe the Clintons can do a good job in supporting Obama -- if they take direction from him and his campaign about what to do.
And my suggestion for Job One for the Clintons is: deliver Arkansas's electoral votes to Obama and the Democratic column in the fall. My reasoning for why this should be their first job (and only, until the first job is accomplished) on the flip.
Arkansas has six electoral votes. That may not seem like a lot, but it's solidly in McCain's column right now, and flipping it would be delivering 12 electoral votes.
Arkansas is also the only state where, credibly, the Clintons' personal ties and political history put them in a position to deliver it. Virtually every other state that could be in play, Obama can win on his own.
Obama's primary victory was built on a combination of the right message, the candidate, and the times, but also very smart campaign strategy and tactics. A good portion of the tactical brilliance was going after every available vote, every available delegate.
The Clinton campaign was "national" and suffered from a lack of local organizing capabilities, the so-called grass roots. I don't see where deploying her, or Bill, nationally will be that effective, particularly with independents and Republicans. Their negatives are far too high.
Except -- in Arkansas. It stands out as a state Hillary would take head to head against McCain that Obama wouldn't.
I don't doubt that given all available time and money, Obama mightn't persuade Arkansawyers to vote for him. But given that there isn't endless time or money, tasking the Clintons with delivering Bill's home state is both achievable and a smart use of resources.