Simple English WikipediaOf course simple words are also helpful for many special needs readers.This is the front page of the Simple English Wikipedia. Wikipedias are places where people work together to write encyclopedias in different languages. We use simple English words and grammar here. The Simple English Wikipedia is for everyone! That includes children and adults who are learning English...
This resource is worth further exploration.
Update 11/21/09: My 12 yo is comfortable reading the simple Wikipedia articles. That's not to say he volunteers to read them, but he's willing and able to read them to earn stickers towards Wii or web time.
I subsequently configured a user account on the family MacBook restricted through Parental Controls to Tar Heel Reader and Simple Wikipedia. This is effectively a homework account, in addition to the web readers it includes Calculator, Grapher, Dictionary/Thesaurus, Google Earth, AppleWorks and the weather, time and calendar widgets.
There was one catch. Simple Wikipedia (and wikipedia) are not compatible with Apple's "Parental Controls". It took all my geekery to figure out a solution (see last update).