I have a confession to make: I am an undisciplined programmer at heart. Unless someone or something provides external motivation to do otherwise, I tend to jump in and start coding a project without ...

the entrenchment of commercial Web application languages — most notably Microsoft’s ASP (now ASP.Net), Sun’s JSP, and Macromedia’s ColdFusion — seems to leave little room for open source alternatives.

For PHP, I don't know, but for HTML I use Tidy. I have no idea how it'll handle PHP, but if you have PHP embedded in your HTML, you probably have bigger problems than making it look good.