A sampling of some of the Gill/Ditko collaborations over the years.
Gill and Ditko created Captain Atom back in 1960, one of the earliest new super-heroes of the Silver Age, and it's a good combination of classic super-heroics, science fiction and early space-age standards. In this story, Captain Adam finds out that a recently launched US spy satellite, Planet X, is going to be targeted by rockets from unfriendly nations, and flies out to space to protect the satellite. A simple enough story, but with a few nice bits of humour and some room for good Ditko visuals. Although in retrospect you can't help but wonder how the Ditko of a few years later would have felt about Captain Atom helping to "negotiate a lasting peace". Negotiate? Why would a man knowingly take poison...
Konga was based on a movie about a monkey who mutates into a giant gorilla. The original adaptation by Gill and Ditko was pretty good, but what I really enjoy are some of the later stories which feature some unlikely but fun continuing adventures of our misunderstood hero. Quite different from the typical "giant monster on the loose" story, there's a lot of humour in the stories, and Konga comes across as a very sympathetic character. It's one of my favourite Gill/Ditko works. In this story, Konga heads down to South America to escape the Arctic chill which gave him a cold, and finds himself foiling the plans of a communist dictator.
Gill and Ditko did a lot of one-off stories in the 1970s Charlton comics, many reprinted in this 1999 collection from Robin Snyder. It's a good variety of stuff, quite a few with some visually inventive little bits, some less serious and others more horror based. This story is about a WWII prisoner of war camp, where the commander and his men are excessively cruel (to the point that they even have to fake reports of the deaths of prisoners to their Nazi superiors). A spy is put among the prisoners and reveals their escape plans to the camp commander, leading to the death of four prisoners. Fortunately, in horror stories death is never the end, and the ghosts of the prisoners exact some fitting revenge.
"Freedom's Star" from E-Man #5 
This is a fairly goofy back-up story presented as a "pilot" for a possible ongoing series featuring Liberty Belle, a super-heroine who also runs a modelling agency in her identity as Caroline Dean. In this story she's called in by the President to prevent the hijacking of a space mission, and ends up replacing the potential hi-jacker and going up to Skylab III to prevent an attack by space pirates. Boy, almost hard to believe this didn't get picked up for a series, isn't it? Anyway, Gill pretty clearly played this concept for laughs, and that combined with Ditko's sense of 1970s fashion make for a potent brew.
"A Man Possessed" from What Is... The Face #3 
ACE Comics reunited Gill on scripts (over plots by Ron Frantz) and Ditko on pencils with three issues of this title in 1986 and 1987. More on the first issue here. In this issue, Tony Trent continues to fight crime under the identity inherited from his grandfather, but finds himself framed for a murder. He also finds out that that there's more to the Face mask than he knew, as a vision of his grandfather leads him to a Chinese temple and some clues about never-revealed secrets, and eventually fights the bad-guys in a foggy airport where a big drug-buy is going down. Gill writes a good script, with a lot of opportunities for Ditko to draw some good action scenes.
Ditko did the following drawing for Robin Snyder's History of the Comics v3#2 , along with a short note on Gill titled "First Choice" (both reprinted in Steve Ditko's 160 Page Package #3 ), where he said "I know Joe's scripts made my stay [at Charlton] and the work enjoyable and worthwhile. Our efforts are worth saving and still enjoyable in reviewing with a long list of favorites."