Although I already have too many books on my To Be Read list, I find myself perusing the giveaways on Goodreads. I usually enter a few drawings each week in various categories. Some are for new releases from authors I already read, but the majority are for authors I'm not familiar with.
If my name is drawn and I'm one of the lucky winners, I try to read the book as soon as I receive it and post a review. I do this for two reasons - one: as an author myself, I know how valuable a good review can be and two: I feel it's a way to say thank you to the author who gave me a free book by holding the giveaway.