A growing list of puzzles can be explored via this page.
You may filter the list by using the search tools at the top of the page.
Select a category from the dropdown, and/or select a difficulty level, (e.g. "Simple" for small children, "Easy" for older children, and "Difficult" and above for adults). You may also just choose a particular puzzle from the "Subject" dropdown.
To see a larger image before doing the puzzle, click the thumbnail to enlarge it.