A tweaked graphics interface, a tagging tool and an extension that provides relevant keywords for associating with bookmarked sites have been named the best new add-ons for Firefox 3.0, following a contest set up by open-source browser developer Mozilla.

Mozilla's 'Extend Firefox' contest is designed to highlight the most useful tools developed for its browser, and this year's competition focused on the recently released Firefox 3.0.

Over 100 Firefox add-ons were nominated, with three received 'grand prizes' in the 'Best New Add-on' category.

The top trio were Pencil, a diagramming and graphics interface tool; Tagmarks, which adds additional tagging icons to Firefox 3.0's location bar; and HandyTag, an extension that provides relevant keywords for associating with bookmarked sites.

Other categories included 'Best Updated Add-on' and 'Best Music Add-on'. Read it Later, TagSifter and Bookmark Previews won prizes in the former category, with an add-on for internet radio site Last.fm - Fire.fm - won Mozilla's praise in the latter category.

"We have seen some powerful new tools and prototypes that we are excited to share. It was hard to determine the winners, but at last, here they are," said Mozilla, in a blog announcing the winners.