Dontclick.it is a great example of interactive design. It is an experimental site where the user interface does not involve any clicks of the mouse. It challenges the user to go through the site using cursor movement alone. It involves various methods for selection and navigation that are all clearly displayed, and interestingly thought out.
Musicovery is a website that uses a simple interface to provide music for anyone in any mood, and genre. The user picks the genre, the era and the dance to tempo ratio and the site plays music which fits into the category. It shows a chart showing the relationship between the song you are listening to and the ones around it. It is a fun way to discover new music, and play what you like where ever you can connect to the web.
Kongregate is a site featuring an astounding array of flash-based games, in many different genres and game types. It also allows people to chat with one another in game and provides achievements and high-score recording to give people more of an incentive to play the games harder and for longer. The site is very well set up and provides great interaction with in games and between people.
