It's not a 'plugin' in the definition of the word, but if you have this app open while playing Audiosurf, it will change your Msn Messenger to display the song you are currently surfing.
As usual, I made this with very little caffeine, so let me know of any bugs you find or any comments / suggestions you have.
Oh and don't forget to actually enable the "What I'm Listening To" option in msn

Edit: beta version disallows multiple instances, tries not to reset your msn status if audiosurf isnt running, has a menu option to manually clear your msn status
Edit 4/29: New version allows full customization of what is being displayed in msn.
You can type in anything you want, and use the two tags {Artist} and {Title} to denote the insertion of the track artist / title.
You can also select between setting the msn tag to Music or Games. The difference being the little icon that shows up next to the tag.
Edit 4/29 - 2:
Fixed a bunch of characters like \ / ñ ö, etc showing up as stuff like %2f in messenger
edit 4/30:
the new patch should fix LockeDowne's problems #2 and #5. i'll take a look at it in a bit to make sure
edit 5/9:
i've included the latest source for this project from my
svn in case anybody wants to poke around with it, mod it, etc
If you want my absolute latest stuff later on, the svn repository is located at
http://pwntastic.thruhere.net:62601/svn/ where the user is Guest
it's a C# solution developed in visual studio 2008. if you don't have vs2008, you can download a free 'express' version from microsoft
if you only have visual studio 2005, there are tools to convert from a vs08 to vs05 solution available if you google it
edit 5/16:
I've added some debug features to MSN Surf. Should it crash, it will now write a crash log which you can then send to me or post here.