Chrome: Chrome's data compression on Android and iOS is a great way to keep your data usage down, but it's only available on mobile devices. If you want to do the same on your desktop, Data Compression Proxy is a Chrome extension that routes all your non-secure traffic through Google's proxy.
If you're on a slow internet connection, or you're using a hotspot on your home computer, you want to keep the amount of data you're downloading as small as possible. This extension helps you do just that by routing all your HTTP traffic through Google servers. This speeds up web browsing and cuts down on your data usage. Obviously, you wouldn't need this on all the time, but it should be helpful for when you're on a slow connection.