I'll do a brief history for anyone that hasn't heard the HaloGrid story -

HaloGrid was creating lots of nice Halo videos for the wonderful Halo community; rabbits were smiling and jumping and rainbows formed and all that crap. Then, one of their videos became so popular, it caused them to go over their allowed bandwidth (ammount of data that is transferred between the server and your computer). Now, normally this would not be that bad, but their evil host Canaca jacked up the prices at the same time that they received over 400gigs of extra bandwidth (h2press usually doesn't use more than a hundred or so, not including video hosting)

Long story short, sign the petition, and make Canaca suffer.