Slate has a version of the Excel-based delegate counter I referenced last week. It is handier and allows you to adjust the margin with a little slider bar. As you adjust the margin, the delegate totals recalculate to reflect the proportional distribution.* At the bottom, it recalculates the total delegates, both for the remaining primaries and overall.
Now, here's the interesting feature. At the top, there's a slider bar that will simultaneously adjust all the contests simultaneously. Guess how far you have to go for Hillary to catch Obama? I'll let you fiddle with it to see, but suffice it to say that the margin she'd need to win in every remaining primary just to pass Obama by three delegates is ... a lot. (On the other hand, Obama would have to win 85% of each vote to win the nomination outright--without supers. Clinton can't win it outright at all.)
No wonder the supers are fleeing the ship.
*True, vote counts and delegate counts are separate matters, but this is the best we got. Math geeks, whinge all you want, but the larger point is true--Hillary's in very serious difficulty