I have developed several Hot Potatoes activities and love the simplicity of use. Once you have created an activity, you can upload it into your course management system, like moodle, for student use or email the htm file to the student directly. Hot Potatoes software is most often used as formative e-assessment tool. It is considered Freeware.
Here is a short video of what a Hot Potatoes crossword puzzle looks like on my LMS, Moodle.
Hot Potatoes has a mac and pc version.