Today I made a TODO list. It has whiteboard sections to write tasks in, an eraser, and a timer. You should be able to use it flat or on the wall, though it's a little bulky to use flat.
The blue is mostly spray paint, with some hand acrylic painting near the tape. The various bits on top are held in place with magnets, which I epoxied.
The cost to make this was $17. $5 for the whiteboard marker, $5 for the MDF board, and $7 for the timer. The eraser I made for free. I already had paints, whiteboard tape, epoxy, and magnets.
Originally I had planned to add a bunch of electronics (LEDs for which task is active, a built-in timer, a buzzer, etc), but I decided not to. I was way too ambitious, so I didn't think I'd have time. On top of that, I was having a rough time getting my microcontroller to work, or figuring out how to mount hardware cleanly on MDF. I don't think I would have been happy with the electronic version (even with enough time to do it well), and I am with this version. I'm glad I gave up on that part early. I don't think I'll attempt another physical electronics project during hack-a-day -- it's too hard with too little to show for it at my skill level.