Balmoral Software has detailed answer guides. No hints.
             The Fool’s Errand      At the Carnival
                             Merlin’s Apprentice      Labyrinth of Crete

I created The Official Fool’s Errand Hints & Answers with paper-and-pencil puzzles with the notion that hints & answers had to be earned.

Barbara Baser wrote the first The Fool’s Errand answer guide.

The answers to 3 in Three — thanks to True Believer John Franklin!
And — what a guy! — here’s a print-friendly version, too.