Tween style blogger Tavi Gevinson has dipped her own toes into apparel design in the past—namely knitted baubles and crotched grocery bags. The results are supercute, if not rising to the level of impulse buy. But this collaborative T-shirt with Borders&Frontiers ($37) is an exception–made of 100% organic cotton, a portion of the proceeds benefit her Clothing with a Cause charity for genocide victims in Darfur (the program originated as Gevinson’s Bat Mitzvah Tzedakah service project).