network stats

A while back, I posted a question to this list:

So, I've still been on the lookout for traffic graphs. I know that many
times the mrtg graphs can be misleading and downright wrong at many times,
but I still think it's neat to be able to see how much traffic is flowing
across various links.

But, it would be even better to know what the aggregate flow of traffic
across the Internet was at any given time. I know it seems impossible to
calculate such a measurement...

For example, if one looks at exchange point stats, like, you can
see that at any given moment in time, that facility is exchanging ~15
Gb/s. Could one add all of the aggregates of the exchange points together?
Would it even make sense to do so? Is CAIDA working on some way to measure
aggregate traffic flow on the Internet?

Something like the following (except that it would be representative of
the entire Internet, not just Abilene) would be really neat.

I have done quite a bit of googling, but have not been able to find any
relevant information.