How to have html not just sitename or logo in site heading block? (via subtheme or preferably editing WITHIN drupal) Can someone give examples of using html not just a text string or logo graphic in the header for a site? 

I ask because I'd like to use several web typography fonts to make a logp rather than a bitmap.

Update

Editing "editing WITHIN drupal" - would be nice, sorry to adjust question. Thanks for your answers so far.
Keep it simple. Just disable the logo in your theme settings and use a block in it's place. You can throw anything you want in there.

Just place a block using Drupal UI into the header region of your theme. No coding, no template files creating/hacking is needed.