First, I should say I can't stand crappy "freebie sites". You know the kind - you go to sign up for a freebie and all the fine print at the bottom says "first you must sign up and fulfill 3 of these offers, meet the requirements.......yada yada", so you sign up for one of the offers and then another, then it requires you to sign up for something else, and something else.....before you know it your inbox is overflowing with spam, you've given away your firstborn - and you never got the darn freebie!!
But -- when you find good freebies to sign up for they are so much fun! I'm always getting stuff in the mailbox - it's like a mini Christmas everyday. =)
So, I will only recommend freebie sites that I know/believe to be honest, real, valuable freebie sites.
One that I've used for a long time is fansfreebies
I also really like Walmart's site - There are usually half a dozen or so samples available. They change often and come in the mail quickly. Right now there are samples for:
Crest Whitestrips Advanced Seal,
Maybelline Dream Liquid Mousse,
I just came across FreeStuff4Free and it looks good so far.
So does this one - Free Stuff Times.