Source code is syntax colorized and beautified for easy reading.
File size and cache header is displayed.
Look and feel can be modified with custom CSS.
Copy to clipboard. Line numbers.
Selected urls can be hilighted in the list of source files.
Open source - https://github.com/tomimick/chrome-ext-view-src
Blog - http://tomicloud.com/2012/07/viewsrc-chrome-ext