iOS: If you're a web developer, checking out the source code behind a website is a common task. View Source is an iOS app that allows you to do it on any page and includes handy syntax highlighting that makes it easy to find what you need.
As an app, you can just drop a URL into it and View Source shows you the code behind it. More useful is the new Safari extension. Just navigate to any page in Safari, tap the extension, and you can view the source right there. You can always get a mobile view by switching your desktop browser's user agent, but this is a handy way to peel back the curtain when you're on the go.
View Source ($1.29) [iTunes App Store]