For more information, please see Wiki Page Editor and Wiki Syntax

Wiki Syntax
Bold text     __text__
Italic text     2 single quotes (').     ''text''
Underlined text     ===text===
Colored text ~~#FFEE33:text~~ or ~~yellow:text~~. Will display using the indicated HTML color or color name. Color name can contain two colors separated by a comma. In this case, the first color would be the foreground and the second one the background.
Deleted text     2 dashes "-".     --text--
Headings !heading1, !!heading2, !!!heading3
Show/Hide !+, !!- show/hide heading section. + (shown) or - (hidden) by default.
Autonumbered Headings !#, !!#, !+#, !-# ...
Table of contents {toc}, {maketoc} prints out a table of contents for the current page based on structures (toc) or ! headings (maketoc)
Horizontal rule     ----
Text box     ^Box content^
Centered text     ::text::
Dynamic variables %Name% Inserts an editable variable
External links use square brackets for an external link: [URL], [URL|link_description],[URL|link_description|relation] or [URL|description|relation|nocache] (that last prevents the local Wiki from caching the linked page; relation can be used to insert rel attribute for the link - useful e.g. for shadowbox). For an external Wiki, use ExternalWikiName:PageName or ((External Wiki Name: Page Name))
Square Brackets Use [[foo] to show [foo].
Wiki References ((page)) or ((page|description)) for wiki references , ((page|#anchor)) or ((page|#anchor|desc)) for wiki heading/anchor references
Lists * for bullet lists, # for numbered lists, ;Word:definition for definiton lists
Indentation +, ++ Creates an indentation for each plus (useful in list to continue at the same level)
Tables ||row1-col1|row1-col2|row1-col3 row2-col1|row2-col2|row2-col3||
Title bar     -=Title=-
Monospace font     -+Code sample+-
Line break %%% (very useful especially in tables)
Multi-page pages Use ...page... to separate pages
Non parsed sections ~np~ data ~/np~ Prevents wiki parsing of the enclosed data.
Preformated sections ~pp~ data ~/pp~ Displays preformated text/code; no Wiki processing is done inside these sections (as with np), and the spacing is fixed (no word wrapping is done). ~pre~ data ~/pre~ also displayes preformatted text with fixed spacing, but wiki processing still occurs on the text.
Comments ~tc~ Tiki Comment ~/tc~ makes a Tiki comment. It will be completely removed from the display, but saved in the file for future reference. ~hc~ HTML Comment ~/hc~ makes an HTML comment. It will be inserted as a comment in the output HTML; these are not normally displayed in browsers, but can be seen using "View Source" or similar.
Direction {r2l}, {l2r}, {rm}, {lm}Insert resp. right-to-left and left-to-right text direction DIV (up to end of text) and markers for langages as arabic or hebrew.
Special characters ~hs~ hard space, ~c~ ©, ~amp~ &, ~lt~ <, ~gt~ >, ~ldq~ “, ~rdq~ ”, ~lsq~ ‘, ~rsq~ ’, ~--~ —, ~bs~ \, numeric between ~ for html numeric characters entity

Because the Wiki paragraph formatting feature is on, all groups of non-blank lines are collected into paragraphs. Lines can be of any length, and will be wrapped together with the next line. Paragraphs are separated by blank lines.

Note that plugin arguments can be enclosed with double quotes ("); this allows them to contain , or = or >.
More help here

Description
User-Agent Info Displays various information about the client.
Anchor Link Creates a link to an anchor within a page. Anchors can be created using the ANAME plugin.
Anchor Name Inserts an anchor in the wiki page. Anchors can be linked to using the ALINK plugin.
Article Includes an article's content within the page.
Article List Inserts a list of articles in the page.
Attachment Displays an attachment or a list of them
Avatar Displays the user Avatar
Box Insert theme-styled box on wiki page
Category Insert list of items with the current/given category in the wiki page
Category Orphans Display Tiki objects that have not been categorized
Center Centers the plugin content in the wiki page
Code Displays a snippet of code
Div Insert a division block, span, blockquote or other text formatting on wiki page.
Definition List Creates a definition list
Fade Displays a label. On click, the block of content will fade in and fade out.
Fancy List Creates a fancy-looking list
Fancy Table Displays the data using the Tikiwiki odd/even table style
File Displays a link to an attachment to a wiki page and can display an image attachment.
Files Displays a list of files from the File Gallery
Flash video Displays a Flash (.swf) file in the wiki page
Footnote Inserts a superscripted footnote number next to text and takes in footnote as parameter.
Footnotearea Inserts a section for collected footnotes in the wiki page.
Google Analytics Add the tracking code for Google Analytics.
googlemap Displays a Google map
Group Display wiki text if user is in one of listed groups
Group List List of groups including a group
Group Stats Displays some stat about group belonging
HTML Include literal HTML in a Wiki page
Iframe Displays an iframe
Image Display images
Include Include a page's content.
Last Modification The last_mod plugin replaces itself with last modification time of the named wiki page, or the current page if no name given
List Pages List wiki pages.
Mail Allow to send mail to groups or user or email directly
Mediaplayer Simple mp3 or flv Player
Insert Module Displays a module inline in a wiki page. More parameters can be added, not supported by UI.
Mouseover Create a mouseover feature on some text
Plugin Manager Displays a list of plugins available in this wiki.
Quote Quote text by surrounding the text with a box, like the [QUOTE] BBCode
Remarks Box Displays a comment, tip, note or warning box
RSS Feed Inserts an RSS feed output.
sharethis Display a social networking tool.
Show Pages List wiki pages
Skype Clickable Skype link
Smarty function Provides access to the tiki smarty functions like button.
Sort Sorts the plugin content in the wiki page
Split Split a page into rows and columns
Stat Displays some stats
Subscript Displays text in subscript.
Superscript Displays text in superscript (exponent).
Tabs Provides tabs built using the smarty tabset block.
Title Search Search wiki page titles.
Table of Contents (Structure) Displays the table of contents for the current structure's subtree as part of the page content.
Tracker Comments Displays the number of tracker comments
User Count Displays the number of registered users
User List Displays a list of registered users
Versions Split the text in parts visible only under some conditions
Wanted Pages Lists ''wanted'' wiki pages
Youtube Display youtube video in a wiki page