Simply validate your site once is not enough. It's very important to keep it validated. This tool is designed to help you with this job. Fill the form box with your page's URL and we will generate a W3C validator feed.
Results get cached, and will update hourly. So, don't use this page to validate your site while coding, use it just to track validation and be warned when a blog post or maintenance coding breaks it.
Comments and suggestions here.