The url validation seems a bit strict, requiring "http:// at the start. No one types that these days, and I think in practice it might be a real roadblock for less computer literate users. I notice also that "ftp://" is valid, but not other protocols like, say, "afp://" or "git://".

Other than that, great job! I'm actually really looking forward to using this in my next project - form validation is usually such a pain.