Do Not Disturb
Description from Knitty.com:
The next time you want a few stolen moments with your sweetie, hang this sign on your door for guaranteed privacy. Bring one with you when you travel, too. You never know when it'll come in handy!
A nice thing about this project is that you don't have to worry about achieving a precise fit or perfect gauge. You can also use up extra yarns from your stash, since it requires very little.
Just remember that the thicker the yarn, the farther away you'll have to stand to read the sign. City dwellers in tight spaces may want to stick with DK or finer gauge unless they plan on reading the sign from their neighbor's doorway. [Then again, if you're trying to dissuade your neighbors from interrupting you, that may be perfect!]
If working with multiple colors makes you nervous, you can always knit the front in plain stockinette and add the pattern later using duplicate stitch.