If it's a great book that I can share and use for reference, I'll get it in a physical copy and keep it. But if it's a book I haven't read yet and I can get it for free on the Kindle, I will. I just went through my Kindle and I have:
44 Classics (like Jane Eyre, Frankenstein, Les Mis, Sherlock Holmes)
95 G.A. Henty books (these are GREAT historical fiction books for teen boys and I got them all free!!!!)
44 Kids books (stuff that was free that I bought for mostly my youngest daughter to read on her iPod Touch)
45 Non Fiction books (cookbooks, how-to books)
214 Theology books
311 "Vacation Reads" - mostly fiction books - books that are just kind of fun reads
100 books from these combined categories that I've already read (although Theology books stay in that category even if I've read them)
99% of these books were free. If I even think I want a book that's up for free on Amazon, I'll grab it for later.
So right now, I'm not buying physical books.