All of them bring the price down to $1.99 aside from one which brings the price down to $0.99 instead. I’m reasonably confident that two of them work internationally and as far as the other 8 are concerned, I’m not sure.

Didn’t use any of them myself, so I can’t guarantee anything.

First of all, here are the two coupons which should work internationally:

RECAP
sideshow

And of course, here are the remaining 8:

99Coms (this is the one that brings the price down to $0.99)
Feast
HINCH199
cjcRMN199
schooL
crAppENs
MIXTAPE
FORK

The most helpful resource for those of you who want to find GoDaddy discount codes as well as coupons for other registrars is Namepros.com in my opinion but be sure to also follow all of the important registrars via twitter since they frequently tweet about new promotions.