I have received fee waivers for upcoming application cycle from below B-schools:
Tepper
Fuqua
Emory
Mendoza
Furthermore, Harvard offers fee waiver in case your annual income is less than $65,000. Some B-schools, such as Darden, do not provide a waiver. Also, there are a few other options - ROMBA, Consortium, etc. but I believe these are applicable only for the US citizens (at least Consortium is).
Key to get these waivers? Attend their events and network.
Unsolicited mention: Many B-schools offer GMAT coupons as well. You just need to ask the admission committee. Though I have not availed any such coupons, but I have got to know about this information from some reliable source.