Practice Grammar, Vocabulary and other subjects like Math, Art or even other Languages.
For each answer you get right, 10 grains of rice is donated to the United Nations World Food Program.
Great chat program, that allows the option of embedding their widget in your website or blog. I used it for a Wetpaint wiki I created recently, and it allows people visiting the website to chat with me when I am on.
Text, image, audio editing and more. They are free, but not illegal apps, mostly open source software (pretty well the entire contents of my computer).
Genial.ly is the best web tool to create engaging interactive visual content (pictures, posters, presentations, etc) for people without programming skills.
I like to use this to keep track of my "To-Do" lists. Great thing is that you can share any of your documents with people, for easy online collaboration.
Excellent productivity and collaboration applications. One of the great things about opening a Zoho account is that you can access your documents from any computer, anywhere.
Google apps offers something similar. I use i google the same way. I would like to add these kinds of collections to my list of proposal topics. They are very easy to use, not intimidating and really add to ones productivity. I've even had my students create igoogle accounts with different tabs for L/W/R pronunciation and vocabulary. It gives them a little ownership and something they can continue to use after the program/course has ended.