I figure, I'm the only person on this blog not to have done some sort of "ranking" on my own, so as its political commentator (of sorts I suppose), I should do something in the skein of a Top Five VP prospects for Obama and McCain...
My rationale for these picks are a few different criteria:
1: Can the VP deliver a state(s) that the candidate would have trouble with.
2: Does the VP deliver some additional skill set that is needed to balance out current candidate.
3: Politically speaking, does the VP balance out the ticket while not endangering the political base of the candidate's core followers.
4: How many Skeletons are possibly in this VP's closet?
That being said, here we go.

1.
Mark Warner (D-VA).
Positives: The man can do no wrong. Quite honestly, he told the democratic party he knew how to win the south and then proceeded to turn Virginia from one of the die-hard red-states, to in-play, to now probably a democratic win this election cycle in Congressional as well as Presidential elections.
Warner would add not only the ability to win the South, but win BIG in the south. He has proven credentials with both parties and can walk that delicate line in the middle of the road.
Negatives: I'm going to draw some heat for this, but I can't get past the idea that there is something seriously flawed with this man's background. He should be Democratic Nominee this year and should have thrown his name into the ring when he saw the weak field of candidates, but he cited "family reasons" as holding him back... I'm suspicious...
Now, if I am just paranoid about this and he IS truly clean, then he additionally cannot be the VP given that he is just more likable in the long-run then Obama will be. Obama comes off as Elitist at times, whereas Warner has a dangerous combination of "Southern charm" meets the Bush-like "Would rather have a beer with" quality.
Yes I know he is slated to be VA's next Democratic Senator, but the man has executive experience, and should not be tainting his record by becoming a low-ranking cog in the Senate.
That and the man is the Key-note speaker at the convention, a sure-fire sign that he is the party's heir apparent (Sorry Hillary fans, it just ain't happenin).
WOW Factor: 5 of 5
Risk Factor: 3 of 5 (he outshines Obama, becomes more popular)

2.
Evan Bayh (D-IN)Positives: Hard-core centrist that can put Indiana and some Midwestern territories into play for the democratic party (and thus hope to pick up even more gains in the very conservative mid-western states).
He does everything right and has his entire career... Which I suppose I have to put into the "Positives" for him (more on that later). He is well connected with the "Party establishment" (ie Clintons), but hasn't alienated the new wing of the party (Dean, Obama and their cohorts). This obviously speaks to his ability to communicate extremely effectively to all crowds and keep everyone happy (Lord knows those people can't or won't).
Negatives: He is quite possibly the most boring pick available...
Seriously, this guy smacks of a better-looking Midwestern version of John Kerry (with far more centrist political values though).
He has spent his entire career not "rocking the boat" (again much like Kerry) and thus has not established himself as anything other then a Democrat that happens to represent a republican state.
He also has made it very clear that he wants to be President one day as well, so with that and his history with the Clintons, I don't see him as a safely motivated pick for Obama at this point.
WOW Factor: 1 of 5
Risk Factor: 0 of 5 (What risk? He has no strong opinions that I can find.)

3.
Joseph Biden (D-DE)Positives: Experience, experience, experience.
The phrase "Been there done that" can be used for all facets of government when it comes to Biden. He is one of the longest tenured members of the Senate and as such has had his pick of most any committee chairmanship he has wanted.
With that comes an exceptionally seasoned candidate with the experience to round-out the relatively inexperienced Obama candidacy (especially in Foreign affairs, as Biden has Chaired the Foreign Relations Committee).
He also tends to add a bit of flair to the ticket in that he can be a bit unpredictable in taking chances on issues (which can be listed as positive or negative, but for the "interesting" factor, I list it as a positive), so he may be more interesting to listen to when we're tired of the "Hope and Change" message later in the election cycle.
Negatives: His age is always a factor in this, as he may not be able to campaign as much as Obama may need him to (granted, he is running against someone with even more health problems, but that may be "fixed" when McCain picks a VP as well).
The biggest issue I have with Biden though, is that he represents a state that Obama doesn't need help with in Delaware. Not only that, but it doesn't seem like he brings any tangible assistance in ANY state that Obama needs help in.
That alone is enough for Biden to not be a serious candidate in this search, in my humble opinion.
WOW Factor: 2.5 of 5
Risk Factor 2.5 of 5 (He's fun to listen to, but he could get them in trouble with off-cuff crap too)

4.
Tim Kaine (D-VA)Positives: Another strong Virginian Politician (haven't been this many for 200 years!) that brings strong centrist values with some real backbone to the ticket.
I like what Kaine brings in that I view him as a fighter that can go toe-to-toe with the Republican attack dogs, while not harming his image in doing so. That is something truly difficult to find in any candidate.
The most valuable aspect of Kaine's nomination though would be his work as a Missionary to Honduras. Quite honestly, having someone on the Democratic side that is that firmly connected to religious "values" (I shudder saying this honestly though) immediately puts a wide swath of states into "playable" for the Dem party in the Presidential, as well as the Congressional races in 08.
Negatives: Kaine is still a relative newcomer to the national stage (as is Obama for that matter), having only become Governor of Virginia 2006. This doesn't exactly inspire much confidence in rounding out the experience of a ticket like that as McCain can run his entire campaign bragging that he has more experience in Foreign affairs then the entire Democratic ticket combined.
Kaine also could rub some of the party faithful the wrong way with his wishy-washy stands on pretty hard-core Democratic issues, such as Abortion and some aspects of Civil/Gay Rights. I think the possibility is there to discourage some of the party faithful to stay home rather then support someone that they just don't agree with.
WOW Factor: 3 of 5
Risk Factor: 4 of 5

5.
Bill Richardson (D -NM)Positives: Foreign Affairs genius with close ties to the Clinton camp that presents a way for the Democratic party to capture the ever growing and ever more powerful Hispanic vote?
What is there not to love about someone that has Executive experience in a mostly Republican state, but also has been recognized for his skill set by being appointed as the US Ambassador to the UN as well as Secretary of Energy?
Negatives: Skeletons up the wazoo and rumors of Alcohol abuse...
Its sad that there is so much possible drama surrounding Richardson, because quite honestly he fits Obama's needs perfectly (over all the candidates named before) for both experience and skill set.
Its possible that the character issues with Richardson are just rumors (and I really hope they are), but obviously the Obama campaign can't afford to have drama coming from the VP office, unless its balanced by the value they're getting (which in Richardson's case is quite high obviously).
All in all, Richardson represents to me the ultimate Wild card candidate, in that his abilities and experience are perfect for the Obama Campaign, but there is that huge IF, in that his past (and possible present issues) cannot surface in a meaningful way in order for him to provide said skill set.
WOW Factor: 4 of 5
Risk Factor: 4.5 of 5
Tomorrow McCain's top 5...