The crossword puzzle maker
To create a crossword puzzle, you need to have at least two words since the words need to be 'crossed'. From that point on you can create more intersections between words and expand your puzzle grid. Luckily, the crossword algorithm does all that hard thinking for us! :)
Adding words revolved around a theme is a very logical and a nice choice to make sure your words cross in context as well as visually :)