iOS/Android: With mobile data caps becoming ubiquitous, anything you can do to reduce data consumption helps. Depending on your OS, Chrome has a couple of options you can use to cut that number down while browsing.
As tips blog Addictive Tips points out, iOS has one option that's not available for Android: disabling the preloading of web pages. To turn this off, go to Chrome's settings > Advanced > Bandwidth > Preload web pages. You can choose to either disable it entirely, or only preload web pages while on Wi-Fi. This should help save you some data.
The other option, which is available for both Android and iOS, is data compression. This used to be a flag that was buried in the Chrome beta, but now it's a baked-in feature for Chrome on both platforms. In iOS, this can be found under the same Bandwidth menu. In Android, go to Settings, scroll down to the Advanced section and enable "Reduced data usage". This will compress websites before they're sent to you, so they will use up less bandwidth on the way to your phone.