Advanced Theme Construction Kit (ATCK)
The default theme of Drupal is okay. Garland is much better than the earlier Drupal default theme but it has some, uh, issues. The typical way to develop a new theme is to start from one of the contributed themes and hack it up. ATCK offers a different route in terms of building a theme from scratch.
Instead of hacking up an existing theme ATCK has you use a WYSIWYG Grid Builder service which spits out HTML to implement the chosen grid. That's your starting point.
However I don't like this support and have deinstalled ATCK.