WikklyText is a Python-based wiki and modular library for creating custom wikitext rendering applications. Its wikitext engine is compatible with the TiddlyWiki markup language. It functions equally well as a wiki-on-a-stick or as a multiuser wiki behind Apache. It includes a Drupal plugin as well.
PottyMouth transforms completely unstructured and untrusted text to valid, nice-looking, completely safe XHTML. PottyMouth is designed to handle input text from non-technical, potentially careless, or malicious users. It produces HTML that is completely safe, programmatically and visually, to include on any Web page. You don't need to make your users read any instructions before they start typing. They don't even need to know that PottyMouth is being used.
SCT (Sphene Community Tools) is a collection of Django applications that are designed to be easily pluggable into any Django project. It currently consists of a Wiki and a Board application. It contains an example project that allows users to create a community Web site containing the Wiki and Board applications without any further coding/configuration changes.