ColdFusion, AJAX and web...
methodName(argumentName=sUsername)
That method I was calling was a wrapper method for another component's
method, and it looked like this:
<cffunction name="methodName">
<cfreturn oAnotherComponent.methodName(arguments=arguments)>
</cffunction>
Spot the error? Yup, should have been argumentCollection=arguments. I must have looked at that code dozens of times, but it didn't click until I explained the problem to someone else.
Moral of the story - if you're having a problem, explain it to someone else. It always seems to work better if you not at your computer and at their computer.. Go figure.