When I read a hard cover I put the flap of the dust jacket over the read pages to mark my page. I HATE dog-eared pages, it seems so disrespectful. For paperbacks- whatever is handy makes a good bookmark - I can't hold on to one to save my life.
Here's another question:
My daughter came home from school a few weeks ago with the task of counting how many rooms in our house had books in them. When all was said and done ... every room in our house had at least 2 books in them. (including cookbooks in the kitchen)
How about you?