Rayslearning is a superb starting point for simulations:    http://www.rayslearning.com/chemsim.htm

This website shows a number of online games available: http://www.sheppardsoftware.com/Elementsgames.htm

There are loads of places to make your instant crosswords. Here are a few  websites http://www.variety-games.com/CW/ ...

The Hot Potatoes suite includes six applications, enabling you to create interactive multiple-choice, short-answer, jumbled-sentence, crossword,...

You can make your own flashcards at   http://www.flashcardmachine.com/ Here is an example for AQA Biology B1 : ...