Today’s lecture for Digital Media Technology was a draaaaag (about tables, frames and forms). I did learn one thing, however: <fieldset>

<fieldset>
  <legend>Some title</legend>
  Content
</fieldset>

Makes a neat looking box:

Some title

Content
 

Of course you can style it to your heart’s content. It’s meant to be used in forms to group data and I don’t know if it’ll tick off the validator if it’s used outside form tags.