W3C Feed validator
W3C: The W3C Feed Validator exposes its Web service as a SOAP 1.2 interface, which you can use in your own applications. [via Robert Sayre]
re: appropriates? Nay, I actually encourage this. I only hope that they keep it up to date (there are significant changes coming this weekend, for example).
As to the SOAP 1.2 interface, I was unaware of this.