There's YouTube Feather which removes all the useless gubbins around a video and allows videos to load much more quickly and explanation for how to make plug-ins click to run, which is useful if you're on the 3 broadband dongle with a download cap I've opted for.
But this is feature with the most benefit so far:
Chrome's custom user agent feature is great if you want to pretend you're using a different browser. If your connection is really slow, pretending that you're using a smartphone has an important advantage: many sites will load the mobile interfaces, which are lightweight. To change the user agent in Chrome, open the developer tools (Ctrl+Shift+I for Windows/Linux, Command-Option-I for Mac), click the "settings" button at the bottom of the window, click "user agent", enable "override user agent", select "Android 4.0.2 - Google Nexus" or "iPhone - iOS 5.0" from the list and disable "override device metrics".I haven't bumped into any obviously mobile interfaces yet, but websites are loading far more quickly since it seems to be using the mobile versions of content like graphics. I suddenly feel like I'm on a much faster connection.
Now it's possible that its simply that my connection/dongle is behaving itself this morning and this is a placebo like perception but even Lovefilm seemed to open more quickly and that usually takes aaaageeess.