Over the past couple of years, I've tried a few ideas to encourage children to write collaboratively using ICT to help. Previous efforts have included Google Docs, which I was told could be done, but I just couldn't find an easy way to enable children under 13 and parents to have individual access to contribute.
However, I have had some success with Wikispaces.com. What I liked about Wikispaces is that the user interface is very clear and simple and the option to register an education account means that you can register a class of children by copy and pasting a class list. You can then accept random passwords assigned to children or you can change them to something easier for the children to remember.
may not always be accurate (like all wikis) and the grammar and spelling may be incorrect but the children are free to correct and make changes as they see fit.
Another valuable tool is the ability to see the history of every change that was made and who is was made by. This means that a pretty accurate assessment can be made of who has a good contextual understanding and where misunderstanding and misconceptions lie.
We have made two class wikis now. One last year about the Victorians and one this year about WW2 which is still being updated.