I'd recommend Boomerangs in Central Square. Boomerangs is really cool and the money goes to benefit AIDS Action, helping prevent the spread of HIV and helping those living with HIV and AIDS in Mass.

There's a donation bin by the church on Cardinal Medeiros Ave and Cambridge St (St Anthony of Padua Catholic Church), but who knows what happens with the clothes - they might just get scrapped for textiles. There's also a Goodwill in Davis.