Last.fm has partnered with Mozilla Labs to add a new music category to the Extend Firefox 3 add-ons development contest started a couple of weeks ago.

A grand prize consisting of a trip to London and VIP tickets to a Last.fm/Presents live event along with a Logitech Squeezebox network music player, will be awarded to the “best new music-related Firefox Add-on that demonstrates excellence in user experience, innovativeness, and use of open standards.”

Extend Firefox 3 runs until July 4th.