The new “Zeldman Made Us Do It!” edition of the W3C’s free online markup validation service includes human-friendly error messages that you can customize, and a “fussy parsing” mode that catches technically kosher but problematic patches in your markup. [Via: Jeffrey Zeldman Presents: The Daily Report]
I tried it on a broken page and it was easier to read the error message. The outline was also handy, along with the pointers about using headings correctly. This should be a useful improvement to the existing service.