NOF Style Sheets - Wasted Space?

I've been going through all of the style sheets -- over and over -- to get
some ideas for the website I'm working on, and I've been noticing a tendency
to have a large.... "blob" on the left side of the page that seems to serve
no real purpose.

Some examples:

NOF 10 style "AMALGAM" has this huge grey block at the left side under the
banner.
NOF 9 style "ARTEMIS" has a large rectangular blob at the left as well.
NOF 9 style "INTOIT" also has this block that seems to cry out for something
to go there.

I thought menus might go there, but all these styles have horizontal menus
under the banner. They're not really a side border, since they only go part
way down the page.

Just wondering if this has a purpose. I tried dropping an image over top in
Page Layout, which didn't work very well.

Is it inteded as a place holder for a graphic? Would the "blob" be edited in
an external graphics editor to place an image in this block?

Or is it some graphic design principle to help readability by creating some
"white space".

I'd be curious to hear how folks would approach these blocks, or to hear
from someone at NO who might comment on these.

Thanks.

RayC