Thanks to Eli Lopian for pointing this out. CodeSpell is a spell checker that integrates with Visual Studio.
CodeSpell bring high speed as you type wavy-line spell checking and full solution spell check to Visual Studio. Using integrated and automatic full text indexing of you source code that understands code punctuation, camel casing, and even ASP.NET and HTML files you can quickly find and fix spelling errors.
The price? $29. Not exactly a bank-breaker. And there's a free trial also.