This area would be a great place for someone like Internet.org to add value, and they've announced some related work, but nothing seems real yet.
It also applies to all network communications, it can't be applied to specific links or connections. On the other hand it's very, very easy to use.
You can configure DummyNet to shape traffic for specific IPs/ MAC addresses etc. - ifpw is you friend.
typo - s/recommanded/recommended/
It would be fairly simple to simulate a saturated upstream though.