Plugins provide a large part of the functionality of nutch. This page acts as an up-to-date resource for supported plugins in Nutch. N.B. There is a wealth of information regarding pre-Nutch 1.3 plugin development available here
AboutPlugins - General information on what plugins are and how they work.
WritingPluginExample - A step-by-step example of how to write a plugin for Nutch-1.3
Writing a plugin to add dates by Ryan Pfister
PluginGotchas - Yep there are some Gotchas you need to consider.
TikaPlugin - Comments on the Tika integration and differences with existing parse plugins
Plugins You can Download
XMLParser_Plugin (parse-xml : parse xml documents using XPath and namespaces)
index-extra - Adds user-configurable fields to the index.
protocol-smb - Allows Nutch to crawl MS Windows Shares folder.
Index HTML Metatags: allows to parse HTML metatags and store them in separate index fields