The latest version is 0.9.5.0 and works with Firefox 2.0.14.
View formatted source is available for download here.
This is the official page for the View Formatted Source Firefox Extension.
View Formatted Source shows the source code (exactly: source code based on the DOM tree) of a web page, well formatted and color coded.
In addition the tool gives you the option to show the CSS rules, including source of the rule, for each individual element in the page.
And if the source code of your page is really big and cluttered, the inline mode gives you the possibility to select in the page the block level element of interest.
In this case View Formatted Source shows only the source code for the selected block level element.
View Formatted Source is available for free in different languages, including English, German, Danish, Dutch, French, Spanish, Italian and Portuguese.
See the pictures for more details:
Please contact me if you have any questions, good ideas or comments.