Autumn is a 2-column theme with a very seasonal look.
Enlighten is a 2-column theme with customizable header image that comes in AJAX and non-AJAX flavors.
GenkiTheme is a 2- or 3-column, widget-ready theme.
Pinkbird is the 3-column Bluebird theme modified for Pink for October.
SEO Streamliner is an SEO-ready theme.
Tumble Hybrid is another tumblelog theme built on Sandbox.