I thought that the use of whiteboard markers was confined to offices which actually have whiteboards, but thanks to the Lifehack.org blog I have been enlightened (once I figured out that dry-erase markers is American for whiteboard markers).
You can use them to write notes to yourself on the bathroom mirror or glass desk (I like this one), or to label frozen food. Another nifty hint - cover an index card with contact and voila, instant reusable mini-whiteboard!
The list fails to point out the golden rule of dealing with whiteboard markers. Make sure you check that the pen is NON-PERMANENT before applying it to any of the surfaces listed above. Let's face it, every office you've ever worked in has some stupid doodle on the whiteboard left behind by someone who broke this rule. Don't be that someone. :)
10+ Things to Do with Dry-Erase Markers [Lifehack.org]