We’ve all known, for quite some time, about the existance of the NLC tool: it’s used during iOS App Testing, under bad network conditions.
However… i’ve (recently.. cough… cough…) realized that this tool can also help you cap OS X bandwith.
This is specially useful when downloading the latest Xcode, and you don’t wanna kill the entire connection, just with that.
You can find the Network Link Conditioner in Apple’s Developers Portal, inside the Hardware IO Tools for Xcode package.