GoDaddy the world's largest ICANN-accredited registrar is offering limited time, super-cheap .com domain registrations costing only $1.19 for the first year, the offer is limited to only one domain per account.
To make use of this special offer you simply need to use special promo coupon code TEST99 while checking out as shown above, you must hurry as the offer may expire anytime.
OYH3 - $3 off / $6.95 any .COM (renewals too... just used it)
BTPS7 - 20% any order of $50 or more
BTPS255 - 25% off any order of $100 or more
OYH1 - 10% off whatever
OYH2 - $5 off a $30 purchase
BTPS50 - 50% off .co.uk domains
BTPS4 - 10% off anything
chill1 - 10% off
chill2 - $5 off $30
chill3 - $6.95 .coms
hash1 - 10% off
hash2 - $5 off $30
hash3 - $6.95 .com registration
gdd1101c - 10% off any order of $40 or more
dp0905c - SAVE 20% on your order of $60 or more (ends 9/7)
Use codes at checkout screen.
UPDATE: You can also check GoDaddy's Today's Offer page for all active offers.
Almost all major domain registrars offer special promotions and coupon codes, so it is always advisable to search for latest coupons codes and offers before buying domains.