Continuing its its fundraising efforts for breast cancer research, Belkin has introduced four new pink ribbon cases for the iPod nano (with video). For each case sold, Belkin will donate $2.50 to help fund breast cancer research through Komen for the Cure (with a minimum guaranteed donation of $225,000). The new pink ribbon cases include the Sport Armband, a neoprene sport case with an integrated screen and Click Wheel protector, the Leather Sleeve,…