The Tiny Style plugin re-adds style editing support to the TinyMCE Rich Visual Editor. The TinyMCE style 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 belogns to Moxiecode Systems, who wrote the style plugin for TinyMCE, which this plugin uses.

This software is licensed under the CC-GNU GPL.
i have been looking for something like this for a long time! i tried using it and it makes my whole mce bar disappear. using firefox’s firebug, i see these two errors
tinyMCE.settings has no properties
loadScript(“http://www.justastupidgirl.com/wp-content/plugins/nextgen-gallery/js/editor_plugin.js”)tiny_mce.js (line 425)
loadPlugin(“NextGEN”, “http://www.justastupidgirl.com/wp-content/plugins/nextgen-gallery/js”)tiny_mce.js (line 396)
[Break on this error] if (tinyMCE.settings.strict_loading_mode)
tiny_mce.js (line 425)
tinyMCE.settings has no properties
loadScript(“../wp-content/plugins/tiny-style/style/editor_plugin.js”)tiny_mce.js (line 425)
loadPlugin(“style”, “../wp-content/plugins/tiny-style/style”)tiny_mce.js (line 396)
[Break on this error] if (tinyMCE.settings.strict_loading_mode)
maybe a clash with nextgen gallery?