As many of you mentioned, lending my tools and even my machines is okay as long as its at my house. Over a period of years I have found my favorite tools, any extras I give away but am kind of possessive about the ones I use all the time.
I don't borrow because I usually am able to buy what I need but I also feel that if anything at all went wrong while I was using it I would feel compelled to replace the item. Not borrowing prevents any hard feelings.