Plugins are mainly user-contributed add-ons that enhance and extend TWiki features and capabilities. A limited number of plugins are included in the core TWiki distribution - and most those can be removed - while the rest are optional, available from TWiki:Plugins/WebHome.
Here is a list of the plugins currently installed on this TWiki site:
SpreadSheetPlugin(any TWiki, $Rev: 18078 (02 Sep 2009) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables and other topic text
CommentPlugin(03 Aug 2008, $Rev: 17791 (02 Sep 2009) $): Allows users to quickly post comments to a page without an edit/preview/save cycle
EditTablePlugin(4.9.1, $Rev: 18014 (02 Sep 2009) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
HeadlinesPlugin(2.3, $Rev: 18123 (02 Sep 2009) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
InterwikiPlugin(28 Feb 2009, $Rev: 14913 (17 Sep 2007) $): Link ExternalSite:Page text to external sites based on aliases defined in a rules topic
PreferencesPlugin(TWiki-4.3, $Rev: 18016 (02 Sep 2009) $): Allows editing of preferences using fields predefined in a form
SlideShowPlugin(02 Aug 2008, $Rev: 17260 (02 Sep 2009) $): Create web based presentations based on topics with headings.
SmiliesPlugin(Dakar, $Rev: 16049 (02 Sep 2009) $): Render smilies as icons, like for :-) or for :eek:
TWikiNetSkinPlugin: (disabled)
TablePlugin(1.036, $Rev: 17769 (02 Sep 2009) $): Control attributes of tables and sorting of table columns