The French shirtmaker Charvet is credited with the silk knot cufflink's introduction in 1904. Many French cuff shirts are often sold with a set of color-coordinated silk knots instead of double-button cufflinks. They add a nice burst of color to your average shirt, but more importantly, they're inexpensive, easy to switch and if you lose one, you won't be too disappointed. Perhaps that's why they've also been called "bachelor's knots."
Knot cufflinks, $9 by Brooks Brothers