Chrome: You can easily convert just about anything with Google, but if you'd prefer a more automatic solution, AutoConvert is an extension that converts measurements mentioned on web pages on the fly.
With AutoConvert installed, all conversions happen automatically to your preferred measurements. You can then mouseover to see the original values or easily toggle the extension off when you're not using it. Whether you're a fan of an overseas cooking blog or you're planning an international hiking trip, AutoConvert makes the process a bit easier. Firefox users can check out Converter for a similar experience.