I am not using so many Firefox Add-ons but this one – ScrapBook – is just great!

You can download it here.

What is ScrapBook

ScrapBook is a Firefox extension, which helps you to save Web pages and manage the collection. Key features are lightness, speed, accuracy and multi-language support.

Functionalities

Major features are:

• Save Web page
• Save snippet of Web page
• Save Web site (In-depth Capture)
• Organize the collection in the same way as Bookmarks
• Highlighter, Eraser and various page editing features
• Full text search and quick filtering search
• Text edit feature resembling Opera’s Notes

Good tutorial here (pdf, 692KB)

Screenshot