Spellify is an awesome textarea spell checker which uses a smooth and effective Ajax based interface. It's written by Nikola Kocic and can be downloaded here: http://www.spellify.com/
I was immediately impressed by the look and feel of this project which uses the Google spelling API but was dissapointed to see that it only supported PHP and .NET.
I haven't tested this massively but it's a simple piece of code and seems to work nicely so I thought I'd get it released so you can get integrating Spellify if you need a spellchecker for textareas on your site.
Let me know if you find any issues with it.
This *should* work with all versions of CF - at least back to CF6 anyway.
Here are the instructions - taken from the included READ ME.txt:
Spellify - Spellify.cfm v1.0 (based on Spellify.php by Nikola Kocic - http://www.spellify.com/)
Copyright (c) 2009 James Allen. (jamesallen.name, www.jwadevelopments.com)
Spellify.cfm is a Coldfusion version of Spellify.php for use with the superb Spellify text area spellchecker.
INSTALLATION (the following is based on the default spellify.php install and using demo.html to test):
1. Download and unpack the Spellify PHP package: http://www.spellify.com/download.html
2. Place it somewhere in your webroot, e.g /wwwroot/spell/
3. Copy Spellify.cfm to the same location as Spellify.php in the Spellify sub-folder (e.g wwwroot/spell/spellify/spellify.cfm).
4. Edit 'spellify/src/spellify.js', line 47. Change:
var defUrl = 'spellify/spellify.php';
var defUrl = 'spellify/spellify.cfm';
Spellify should now be working with Coldfusion. You will probably have to change the defURL when you implement the code on your site (e.g /functions/spellify/spellify.cfm etc).