In case you have some classic webpage, like Anton Ertl for example, you're very lucky. You can change your design completely by using css wisely. And you can beef it up semantically by looking for better tags.

Oh, some things Mr. Schatten mentioned in today's eCommerce 1 lecture about tagging, which are rather important:

• Please don't use h2 only because it's smaller, when you have a level 1 heading and should use h1 instead.
• Get away from presentational html. This includes but isn't limited to
  • b and i. Why would you like to add bold or italics to your text, when you mean emphasis (em) or strong emphasis (strong)? Poor webdesigner...
  • abuse of b and br or similar tags, when you rather should use a heading (h1, h2, h3, ...) or a definition list (dl)
  • use of br, except of, say in listings, when you should rather use paragraphs (p). Remember: you can style them as well, think about margins and display inline.
• Use lists, when you have lists. Have a menu? A unordered list comes to mind. Have a numbered list? use ol.

Classic websites aren't as hard to find as one might think. Loads of software gurus tend to have it and use it as a quick way of transmitting thoughts to a broader audience. Which is exactly, what html was meant to be used for in the first place.

Structural vs. Semantic

Strict vs. Transitional XHTML