WP Code Highlight provides clean syntax highlighting and it also provides a code button.
Adds a button and keybinding to the WYSIWYG (visual) editor to mark text as inline code.
SmartAss Highlighter is extremely simple and easy to use syntax highlighter for your code. Shortcode - [highlighter]
Adds PrettyPrint and Code buttons in TinyMCE editor to quickly mark text as code, add 'prettyprint' class in 'pre' tag.