The Tiny XHTML plugin re-adds the xhtmlxtras plugin support to the TinyMCE Rich Visual Editor.
The TinyMCE table plugin is normally bundled with TinyMCE, but it has be removed from the version within WordPress This plugin puts it back in.
Most of the credit for this plugin belongs to Moxiecode Systems, who wrote the style plugin for TinyMCE, which this plugin uses.