EDIT: The Coupon is now for 25$ and not 100$
Woah… Microsoft offers 50$ coupons and now yahoo is offering 100$ coupons! But only for new signups. If you dont see the 100$ coupon on the page from the link above enter USCJ16 manually to get it.
No word on the specific time limit on how long this promotion is lasting. I just got a email from a yahoo rep with that code.
(I think they were jealous of all the attention Microsoft Adcenter got below)