Gary B. Larson has a site with links, books, and organizations. There is the Plain Language Association International . Most of their consultants are in Canada. One of the US consultants is Prof. Kimble, a law professor from Michigan, who wrote a defense of plain English . He is also the US representative for Clarity.
Clarity is a worldwide organization promoting clear legal language.
The English are represented by The Word Centre and the Plain English Campaign . The European Commission's Translation Service has a fun site . The Australians have a wonderful site by the Department of Employment, Education, Training and Youth Affairs . South African Robert Gentle has a site at Plain Business Writing . His booklets are very good examples of plain-English writing and document layout.