The PHP SpellAsYouType Class allows you to spell check in the context of you page.
Any activated textarea will develop "red wiggly underlines" under all spelling mistakes - and the user can correct them on right click.
This behavior is server efficiant, requires no client plug-ins - and words on all major web browsers including Internet Explorer (IE).
The SpellAsYouType class allows the developer a great deal of customization, choice of languages, translations and so forth.
<textarea id='myTextArea'>Content</textarea>
<?php
require "/phpspellcheck/include.php"; // this path must lead to you PHP Spell Check Install folder
//For inline "spell-as-you-type" on right click
$mySpell = new SpellAsYouType();
$mySpell->InstallationPath = "/phpspellcheck/";
$mySpell->Fields = "ALL";
echo $mySpell->Activate();
?>