John

This plugin enables you to highlight syntax using the PEAR Text_Highlighter class. Other syntax highlighters that use GeSHi have slower rendering speeds which will increase your page load time. However, this plugin gives you the speed and efficiency provided by the PEAR developers. You even have the option of enabling or disabling the line numbers as well as specifying your own style.

Ion Snytax Highlighter

This plugin allows users to highlight code.

agmorpheus

Syntax Highlighter ComPress is a simple WordPress plugin, that is based on the latest <a href="http://alexgorbatchev.com/wiki/SyntaxHighlighter" rel="nofollow ugc">Alex Gorbatchev’s SyntaxHighlighter Script</a>. Code and source text of different mark-up or programming languages can be highlighted in WordPress.
There are other WordPress plugin based on the SyntaxHighlighter Script but these cause long page loading times and they are difficult to handle. The advantage of Syntax Highlighter ComPress is that only necessary brush files will be loaded dynamically. Another advantage is that your code can easily pasted into your posts, no need to replace all ‘<code><</code>‘ with ‘<code>&lt;</code>‘.
Supported mark-up or programming are: AppleScript, ActionScript3, Bash/shell, Coldfusion, C#, C++, CSS, Delphi, Diff, Erlang, Groovy, JavaScript, Java, JavaFX, Perl, PHP, Plain Text, Python, Ruby, Scala, SQL, Visual Basic and XML.
The plugin is localized in English, German and Romanian.

Syntax Highlighter Compress

Syntax Highlighter ComPress is a plugin for code syntax highlighting. It loads fast on the website and code can pasted easily into Wordpress.

Ion Snytax Highlighter vs Syntax Highlighter Compress