Coupons you can print free? Nope.
Discounts you can buy the right to use? Yes.
Landry's Restaurant Group (who own/run TRex & Rainforest Cafe, as well as Yak and Yeti) has a club you can join ("Safari Club") which gives you a choice of free appetizer or 10% off a party of 4's entrees; a merch discount of something like 10%; and a couple of other minor perks - priority reservations, I think, as well. Membership is something like $15-20 a year for the family, so you'd have to figure out if you'd save enough to justify that expense of joining.
Incidentally, within WDW the Safari Club stuff is only valid at Rainforest and TRex, not at Yak and Yeti.