A tool that offers a great set of tools for masters or narrators which play a d20 system pen&paper gdr (like D&D). It is specifically designed for D&D but there are lots of generic tools inside that can help in other types of rulesets and/or campaign settings.
At the moment I write (July 8th 2012), I have mainly completed the Character Name Generator (Codename RNG). It works nearly smoothly and can be installed as a 0.1 version of the entire d20 Master Tools package. The 1.0 version is scheduled in an unprecised date, just when I finish to write all the functionalities of the desktop version of the tool. You will find it in my GitHub account as soon as possible.