I understand that there are, at least some, Geocachers who like to solve jigsaw puzzles and think they have appreciated a “jigsaw list”.
With a simple search for 'flash-gear.com', 'jigsawplanet.com', 'jigzone.com' and '%jigidi%' in the cache descriptions you get most puzzle caches and as it’s almost a "run once" search it shouldn't burden your server farm to hard.