Mozilla today announced winners of its Extend Firefox 3 contest after reviewing over 100 extensions.

One of the grand prize winner of Best New Extensions is Pencil by Dương Thành An, which adds GUI prototyping and diagramming to Firefox using the Firefox’s SVG support for rendering and scripting.

Other Best New Firefox Applications are Tagmarks and HandyTag, which extend the bookmark tagging feature of Firefox 3.

Tagmarks adds a set of icons to Address bar which let you assign tags to your Bookmarks easily instead of using only single star.

HandyTag suggests tags for your bookmarks by fetching tags from various sources based on the bookmark.

The winners of Best Updated Add-ons are Read It Later, Tagsifter and Bookmark Previews while Fire.fm grabbed the Grand prize for Best music Add-on for Firefox 3.