Dry erase markers are wonderful inventions. Not only can you use them to write on the special dry erase boards, but they also work well on glass. You can use this to leave notes in some pretty interesting places.
For example, you can write notes on your bathroom mirror where you will be sure to see it in the morning. The window in your office can also serve as a nice impromptu whiteboard. I have a large desk made from a thick sheet of glass over a frame, so I can use dry erase markers to write directly on my desktop.
Obviously, having everything you write in a neat wooden framed whiteboard is less messy and looks more organized, but sometimes doing something out of the ordinary is what it takes to get results that are out of the ordinary.