Disclaimer: I 'do HTML' for a living and get paid well too.
I've always used 'Web Developer' or 'UI Developer' for a title, but 'UI Engineer' does have a nice ring to it. First off, no one is going to pay anyone to just 'do HTML'. Writing HTML, even well formed XHTML Strict compliant HTML is not that complicated. I wouldn't pay someone to just write HTML. It's the extras that count. CSS expertise, including cross browser incompatibilities and work-arounds, make a 'Web Developer'. Extensive knowledge of Javascript libraries, events, and cross-browser incompatibilities make a 'Web Developer'. Working knowledge of PHP, Perl, C#, Java, and a host of templating engines and content management systems make a 'Web Developer'. My little sister can 'do HTML'. You should see her MySpace page. You hire a 'Web Developer' or 'UI Engineer' when you want to have that professional appearance for your website, properly search engine optimized and 508 accessibility compliant. The website that works in all browsers, degrades nicely for the older browser crowd, and is still cutting edge enough to do all the fancier stuff that's now considered 'Web 2.0'. </rant>
So what do call a people that 'do HTML'? Interns.
Aero