Nathan Rice shares an clever technique to serve your IE6 visitors the Default WordPress theme (or any theme, for that matter). He even wraps it all up into a nice plugin that you can use for your site. I think this is a good middle-ground between completely ignoring IE6 and breaking your back trying to accommodate it. You could even design an "all-purpose" theme for IE6 to streamline new site development. Drag, drop and done.