WIth Richardson's endorsement today, it is time to start talking about running mates for the overwhelming likelihood that Obama becomes the Democratic nominee. Some of the more obvious choices after the break, and add your favorites in the comment threads
Governor Bill Richardson - adds Foreign Policy experience (UN Ambassador), Domestic policy experience (Secretary of Energy), a sitting and popular Governor, and yes, Hispanic despite having a fairly "Anglo" surname.
Senator Hillary Clinton - I don't think she would take the job, but she is an articulate and seasoned professional that might, just possibly, help everybody on the Democratic side come back together. As VP, she is much less likely to really energize the wingnut base that have hated her for so long. She also helps in the working-class white states like Ohio and PA (Obama would win CA and NY regardless of running mate).
Former Senator John Edwards - a good "new politics" choice, great orator, and telegenic for all the ribbon cuttings VP's tend to do. Not likely to help with the experience issue, particularly on foreign policy. He puts both Carolinas even more in play.
General Wesley Clark - scores points for Foreign Policy gravitas, and brings some of the successful aura of Bill Clinton's Kosovo intervention (i.e. where the US was actually greeted as a liberator, did the job, and went home) as to mollify folks who yearn for a bit of Clinton without the controversy. He's also from Arkansas
Senator Jim Webb - Virginia Senator and former Secretary of the Navy (under the Patron Saint of Conservatism Reagan) Knows more about Foreign Policy and the Military than McCain. Appeals strongly to the testosterone voter and has an unimpeachable patriotism. Has a son in Iraq, won an EMMY, and forgot about the gun in his assistant's briefcase (so the NRA rank and file love him)
Al Gore - very unlikely he'd take the VP slot, as it is hard to imagine he could do more for Global Warming as VP than as Al Gore, Citizen Extraordinaire and Winner of Every Award You've Ever Heard Of. As POTUS, he could do more, or perhaps as Secretary of Energy, but the VP slot makes little sense.
Senator Chris Dodd - solid foreign policy credentials, looked very presidential as a candidate (just not popular enough). Balances out the Joementum's efforts to elect McCain in Connecticut.
Former Senator (and Olympic Gold Medalist, Hall of Fame NBA Champion, Rhoads Scholar, Eagle Scout, etc.) Bill Bradley - Almost always the brightest guy in the room, with long-established labor and working-class hero credentials. Not the orator that John Edwards is, but the case can be made that Obama is orator enough not to need any help.
Other names worth considering that come up in these conversations: Governor Kathleen Sebelius, Governor Brian Schweitzer, Senator Blanche Lincoln, Senator Jack Reed, and many more that will emerge in the comments.
Have at it.
more background info on many of these can be found at nocore's excellent VP candidate roundup diary from January (updated a few weeks ago, but before Elliot Spitzer's political demise)