Adapro is a customizable multi-user word processor originally geared towards users with a learning disability or developmental disorder, such as dyslexia or autism. Hence its array of assistive features, including inline representation of words through pictograms, a virtual keypad with configurable phrase buttons, a dyslexia-friendly font, PBDQ, and high-contrast modes. The editing interface can be customized on a per-user basis, and documents produced with it can be exported to RTF for further editing in OpenOffice or other software. If Java 6 is on the system, it doesn't even require installation.
TinyIB is a lightweight PHP image board which emulates the functionality of 4chan. If you use MySQL or SQLite, you can use it to create an efficient setup able to handle large amounts of traffic. If you don't use a database, it can store posts as text files for a portable setup capable of running on virtually any PHP host.