I think the Paul Dini/Bruce Timm DC animated universe needs to be mentioned for bringing a lot of lasting influences to the comics. A number of original characters from the shows found their way into the DC Universe proper--Harley Quinn, Mercy Graves, Renee Montoya, Lock-Up, and probably a few others. DCAU takes on established characters heavily informed the comics as well... Chief among these would be Mr. Freeze, who never had much of an interesting origin/backstory prior to the animated version. The tragic ex-scientist seeking to revive his wife has become the accepted comics version of the character.
It was the DCAU that brought Batman back to the classic no-yellow-oval look, too (although Frank Miller had also used that look in Dark Knight Returns, the mainstream comics didn't adopt that look until after the animated series went there--kind of a radical idea at the time). Furthermore, the animated version of Green Lantern John Stewart led to a revival of that character in the comics. Prior to JL/JLU, John hadn't been a ringwielder in the comics for some time, serving as an occasional supporting character in the Green Lantern books. After the show gained popularity, John returned to active duty in the books, strongly resembling the animated incarnation in costume and hairstyle. Since then, the animated Stewart's Marine Corps background has been retconned into the comics, as well (the comic Stewart was an architect by trade--which remains the case--but he had never been depicted as having prior military service until recently).