Over at Mozilla Labs, they have announced what they call the Extend Firefox winners, which list add-ons voted as the best by a team of judges. Some of the add-ons are still under development but as Mozilla Labs states are still powerful news tools for Firefox 3 users to take advantage of. Some of the new prize winners include:

Pencil by Dương Thành An

GUI prototyping and diagramming that everyone can use.

The Pencil Project’s unique mission is to extend Firefox 3 to an opensource tool for making diagrams and GUI prototyping that everyone can use. Pencil makes uses of the SVG support in Firefox 3 to implement all the shape rendering and scripting.

Tagmarks by Felipe Tassario Gomes

One click bookmark tagging

This add-ons adds a set of icons to the quick bookmarks, allowing you to quickly add tags to your bookmarks by clicking on each icon.

HandyTag by Rémi Szymkowiak

Automatic bookmark tagging

HandyTag simply providing a complete set of most relevant keywords in the bookmark’s edition panel. These keywords are retrieved from many different sources.

There are many other award winning add-ons that came in as runner up, but also may be useful to you. May I recommend you take a look  at the Mozilla Lab web site for additional information. There appears to be something for everyone.

Mozilla Labs.