I'm rather new to WP and Thematic. The main reason I'm using WP/Thematic is I saw a nice site that seemed to have multiple primary columns, i.e., not just one primary and two sidebars, as your available "3c" layouts provide. Here's the site: liaworks.com which seems to have three narrow columns, plus the sidebar on the right. Or are those boxes some sort of plug-in? My own site, velomarais.com has a roughed-out version of what I sort of want, but the liaworks.com is what I'm really after.
BTW, is there a good book or tutorial on serious customizing for WP/Thematic someone could suggest?