Another variant which is actually done by the big enterprise eWhatever
companies with servers in multiple locations at a big colo provider is the
95th percentile monthly backup or db exchange. They'll push gigabit(s)
between facilities for exactly under the mark where they'd have to pay for
it, and they're not always nice enough to warn you before hand.
For those colo providers, who have a model of dumping traffic out to peers
locally and usually don't have a longhaul backbone capacity which is
significantly larger then those "big" customer interfaces... Well you get