Validation. It's an important element to production of those pesky websites. Probably more important and more awkward than it should be. No, scratch that, deffinately more awkward than it should be. But that's not all there is to making a decent website, oh no sir. Content, variety, conformity, tracking. I wish we got to work with clients who grasp this stuff a little better. - But then, perhaps we need to explain things better?
Sitescore, from Silktide, has just appeared back on the scene. (they were 'down' for a few weeks while they upgraded their services) Few online validation tools can be used on their own, and Sitescore is one of those. Pop in your URL and it'll check anything and everything from validation, to googlerank, image variety to reading-ease and even plagerism. Plus, the website is fun and easy to use. I just wish I could have it as a desktop app.
While I'm on the subject, there's also WebXact, from watchfire (formerly Bobby, I believe) which is a less-pretty and more techie website validator. And of course, there's the Firebug extension for firefox and the IEDevToolbar for IE. Both of which plugin to your browser and offer inline page debugging and links to common validation services.