Is it worth a back-end developer's time to get into web-design and HTML/CSS
inerte: Yes, it is worth, specially since you're making a website, even if you're going to hire someone. You can at least glance if they're doing correctly, as far as you will know.HTML/CSS isn't hard. And you need to consider if what you're doing will work on multiple browsers, including mobiles. Knowledge about this will mean more visitors, and thus more money.Now, creative... that's another question. A good design, in the strict aesthetics sense of the word, is very hard. In fact, for some people, it's a whole career :)Also, while I don't recommend going for the aesthetics route, there's much more involved in webdesign. SEO, usability, accessibility. You should be able to take a pretty PSD from a designer, and develop with ul/li for menus instead of using Flash, for example.