Luther recently posted a Twitter where he wondered whether anyone was still interested in his old series. Personally, I'd love to see a continuation of Horace's Curse (part 2). Maybe the ring and whistle could fall into the hands of two different people who don't know their properties. The whistle's holder (maybe a small child) uses it as a toy, while the ring's wearer (his mother?) tries to figure out why she keeps spontaneously inflating at inconvenient and embarassing times.
Another series with lots of potential is Carnatic's Remotes (part 2). Having the inflation under literal remote control opens all sorts of possibilities for blackmail and coercion. And what if the signal gets crossed with, say, a garage-door opener or cell phone?
As for individual stories, FunkyOBrian wrote a story (not available here, but it's around) called Taki's Peril. The ninja girl from Soul Calibur was planning to use a helium pellet to inflate her bodysuit to keep from drowning in a river. It never got to any inflation, unfortunately, but the potential is there ;)
So what stories or series would you like to see more of?
I wouldn't mind seeing a sequel to "The Cargo", it is an all time fav story of mine. If I had the money, i'd turn it into a cartoon.