Snowball fight in Times Square, 2009
Nothing beats the good ol' give-em-hell-and-charge-into-the-flurry tactic.
These photos are Non-commercial Creative Commons. Feel free to use them for whatever, attribution would be nice. If you need a bigger version for a print, feel free to ask.
My blog also has large versions
Also, if you just can't get enough about this snowball event, check out photog Doug Kim's work, which was featured on CNN.com. They're black and white and better action shots, IMO.