Okay, first of all, there aren't any trainers or hex editors for Nancy Drew: Secrets Can Kill, because Nancy has no stats, skills, hit points, or anything else you could
conceivably want to edit. I'm really surprised how many people ask me for that sort of thing. The only way to really cheat in this game is to look up the
solution to a puzzle rather than figuring it out yourself. If you want to do that, or you just want to learn more about this game, here are a few good
links for you:
Universal Hints System is a great place to get a spoiler for one specific puzzle you're stuck on without accidentally ruining any of the rest of the game--they have
their walkthrough uniquely structured to reveal only one hint at a time.
Here is Her Interactive's homepage, with patches, technical support, and forums covering all 15 of their Nancy Drew adventure games.
Very explicit walkthrough, lots of spoilers and screenshots of puzzle solutions.
Wikipedia article about Secrets Can Kill,
giving the history and source behind the computer game.
The rest of these links aren't related to Nancy Drew: Secrets Can Kill, but you may enjoy them anyway... most of them were created by me or by friends of mine. (-: