Superman and Batman as a gay power couple (The Authority): Ellis ported Superman analogue Apollo and Batman analogue Midnighter from Stormwatch to The Authority. In their new book, the two were revealed to be a gay couple. Back in 1999, this didn't happen all that often, and so the book received a GLAAD award. Arguably these two paved the way for other gay couples in comics such as Northstar and Kyle Jinadu, Batwoman and Maggie Sawyer, and Wiccan and Hulkling.
Right-tool-for-the-job expert-dispatch service (Global Frequency): This 2002-04 Wildstorm book may be the best example of what happens when Ellis favors concepts over characters. Global Frequency was a 1,001-member organization (about on par with Jonathan Hickman’s Avengers cast) of the world’s foremost experts in their field, who are called in as crises warrant based on field of expertise and proximity. In a way it was like a super-serious version of G.I. Joe, with a mix of military, intelligence, scientists, ex-cons and the like all working to save the world, except the characters didn’t stick around long enough for anyone to decipher who the Shipwreck and Roadblock analogues were. Even the artists changed from issue to issue. Also it was almost a TV show.
The guy who buggers cars (Two-Step): In 2003-04, Ellis wrote a quickie three-issue miniseries for Wildstorm with Amanda Conner and Jimmy Palmiotti about a bored, cheeky London camgirl named Rosi and a zen gun-for-hire named Tony who run afoul of a gang whose trademark is having artificially large wedding tackle. Among their number is a Baby Huey of a man named Ron who enjoys having sex with cars to the point where they explode. According to TLC’s My Strange Addiction, this is a real thing.
Having Iron Man inside you (Iron Man: Extremis): In 2005-06, Ellis got to tinker with Iron Man's origin, tying the creation of the first Iron Man suit to the war in Afghanistan as part of a six-issue arc that introduces the concept of Extremis, a nanotech virus that allows fir the constant healing and enhancing of the body in the latest attempt to re-create the Super Soldier Serum that transformed Steve Rogers into Captain America. Tony infects himself with Extremis and in so doing becomes one with Iron Man, allowing parts of it into his bones and give his brain a complete upgrade. Elements of the Extremis story were used in the Iron Man movies, including the updated origin story.