Since I realize writing full blown adventures that can be used in any series can be a daunting facet, and the Narrators are likely to alter them to fit their own needs anyway...I think a book of seeds would be great.
Say a book, organized in "types" of adventures, with one page front and back seeds of adventure ideas would be handy.
Categories could be like:
Bottled (takes place entirely on ship)
Brave New Worlds (planet-side on non-Fed worlds)
#Species# (adventure seeds about a specific threat species)
Showing the Flag (adventures involving Starfleet interacting with a Fed Member world or colony)
Red Alert (seeds that revolve around the use of prevention of the use of Star Ship force)
Now, I know that I personally could probably churn out a "seed a day" for months and I'm just some guy..real talented writers could probably churn out really cool stuff that the rest of us could just build from with less "tinkering to fit".
I would buy "lots" of books like that, because I just enjoy the seeds for themselves, and the best ones I would actually use.
Peace