The Geological Society of London revamped their website a couple of months ago or so. It's basically the same site as before, but better organised and with a much nicer layout and design. Thumbs up for this!.
One of the things I like the most is the "Online plate tectonics" site, aimed to students aged 14 - 16 (I personally think any person will enjoy it, at any age). The site starts with an interactive introduction to the distribution of plate boundaries, volcanoes and earthquakes. It has also sections on the pioneers of plate tectonics, explanations about the geochemical and geomechanical properties of plates, and how the plate tectonics have shaped the geography of the United Kingdom. It also counts with tests and glossary areas, where the young visitor can check their knowledge and find answers to their questions.The teachers also have their area, with indications and guidelines.
A great initiative for kids, teachers and general public alike. It doesn't matter how much you know about plate tectonics, you will like this site and you will bookmark it!