I´m surprised actually, that I don´t find more creative uses for "sidebars" on WordPress sites.
You could use "sidebars" with plugins/widgets almost anywhere in your template.
See how I used the category tag cloud plugin in the header of http://www.eliZZZa.net/
So maybe an idea for further development could be, to see "sidebars" more as "containers" for various functions.
I´m interested in your opinion!