The "Debug Console" is a very usefull javascript-program that lets you test and debug your own javascript-programs very easely. It lets you survey objects, variables and functions and it's even possible to execute functions manually via console!
Developer: trueworld.ch Platform: all Date upd:2003-12-01 Hits1379 [Download] [Visit]

A method to get the styles on an element that aren't set in-line or with JavaScript.
Developer: Justas Vinevicius Platform: Date upd:2007-02-20 Hits190 [Visit]

System Color Palette is an interactive palette containing the CSS3 System colors. Clicking on the color entries in the palette will send the color's name to the text field, where it can be copied and pasted directly into your style sheet.
Developer: codehouse.com Platform: Date upd:2004-09-04 Hits1658 [Visit]

This script is used to encode / decode UTF-8 data
Developer: Justas Vinevicius Platform: Date upd:2006-09-09 Hits2136 [Download] [Visit]

Cross-platform JavaScript method for retrieving style information set in either a CSS style sheet, a style block, or inline
Developer: codehouse.com Platform: IE 5+ Win/Mac and Gecko family Date upd:2004-07-23 Hits730 [Visit]