365psd is a website where you can download a Free PSD every day. Today is day 24 and they are giving social media icons. You can download it here
You can check the old ones by using the previous button. Each one is tagged too, so you can click on the tag to see all the uploads so far in that category.
Day 9 http://365psd.com/day/9/
Day 18 - http://365psd.com/day/18/
Day 13 - http://365psd.com/day/13/
Day 11 - http://365psd.com/day/11/