Links to Charities to donate knit/crochet items to.  Be sure to check the item guidelines for specific requirements for each group.  They do vary.  

In addition to the groups listed, it's easy to donate in your community.  Keep a hat in your bag to give to a homeless person when your paths cross.  Drop some slippers off at a nursing home.  Leave some hats with the school counselor at an elementary school.  They know who needs them.  Missions, shelters, clinics - just google a bit and you'll find people in your area who would be happy to take 1 or 100 hats.  Or scarves.  Or Gloves.  

http://www.nationalww2museum.org/learn/knit-your-bit/how-to-participate.html

http://www.soldiersangels.org/

http://marinecorpskids.blogspot.com/

http://www.operationtoastytoes.org/chapters.html

http://www.thehugsproject.com/

http://www.theshipsproject.com/Home.htm

https://www.facebook.com/HatsForOurVeterans

http://www.hatsofhope.com/