Even during the keynote when the newest iPod Nano was introduced, Steve Jobs mentioned one of the Apple execs intended to adapt it as a watch.
There is no shortage of watchband options out there, but one of the coolest I've seen is this one, using a classic 3/4" 'The Band' from Chums. This replacement watchband has been a fan favorite for decades among sports/outdoor enthusiasts.
The 20mm (standard) size is the perfect width in my tests to securely clip on the iPod Nano. And with hemp, standard or wide band options in 20mm size, everybody should be able to find one that suits them well.
$6.99 is also a steal in comparison to many of the other iPod® Nano watchband options and The Band has been around since the 1980's, improved and perfected as the world's best replacement action sports watchband option.