FirePath is a Firebug extension that adds a development tool to edit, inspect and generate XPath

https://addons.mozilla.org/en-US/firefox/addon/firepath/

Radaee PDF Reader

https://play.google.com/store/apps/details?id=radaee.pdf

Good map source code

https://code.google.com/p/mapsforge/wiki/MapsforgeApplications

Making Good Software

http://www.makinggoodsoftware.com/2010/05/27/10-things-they-never-teach-in-college-about-programming/

Code review.

http://insidecoding.com/2013/01/07/code-review-guidelines/

http://www.javaexperience.com/code-review-checklist/

https://gist.github.com/srivastavarobin/8954241

Chrome browser into a powerful code viewer

 Turn your Chrome browser into a powerful code viewer that brings Android and Java code snippets to life. The Codota extension analyzes code snippets in web pages and gives you the ultimate code browsing experience.
http://www.codota.com/extension?utm_source=youtube&utm_medium=in%20stream&utm_campaign=ext%20video%20promo

You to see what data is sent and received between a web browser and the server

How to Set Up Charles Web Debugging Proxy for Android Devices and Mac

http://university.utest.com/how-to-set-up-charles-web-debugging-proxy-for-android-devices-and-mac/