I’m not sure how I missed it, but a new feature to OS X Lion is a Preference Pane called Network Link Conditioner. This is a thing of beauty for Web developers the world over; built in network throttling on an OS level.
Charles, at a very high level, was a proxy that you could direct your requests through and it would throttle how fast things took place. The recording tools were awesome, but way beyond what I was needing to do. The other issue with it was a required dependency on a Firefox Add-on. With that, you could only simulate alternative network conditions in a single browser.
Network Link Conditioner changes that by offering an altered connection on a system level, allowing you to throttle your bandwidth top to bottom. The pref pane gives a number of options for throttling too:
All in all, I’m really excited to have discovered Network Link Conditioner. Unfortunately, it’s limited to OS X Lion, so if you haven’t upgraded the preference pane won’t be available. If you have upgraded, Network Link Conditioner is not installed by default, but you can find it and install by double clicking
/Applications/Utilities/Network Link Conditioner/Network Link Conditioner.prefpane — enjoy!