Not just messages but messages with media. We were looking for and talking about curriculum that contained videos, powerpoints, pictures, audio, etc...
Pastor2Youth...sign up for a free membership and then click the "YM Exchange" in the top right corner. There are several resources in here (backgrounds, powerpoint games, hundreds or group games, and yes...messages. And if you feel you have some things great to share just submit it)
Chemtastic...Lots of good free stuff here...and message powerpoint
Simply Youth Ministry...also check out their freebies link
24/7...put together by a youth group, never saw it but want to check it out.
Dean Hawk...I have never used these but there were a recommendation from within the group. There were described as creative with good powerpoints. Check them out.
Bluefish...Loads of 4 week DVD curriculum and video series
Youth Resource...$20 for all you can download. I was in this a few years ago, they did not put new stuff up enough and it was $10 back then, but i say if you are looking for some help it is probably wirth $20, download everything you can and do not sign up for a second year...maybe every other year or so.