The Nelson style ball clocks are great. It goes well on a plain wall - by itself, as Sandi demonstrates here in her happy modern danish apartment.
This is from Apartment's Therapy House Tours 2008: Karen Kimmel and James Bond's place (no, I'm not kidding).

This is the fully licensed Nelson classic, reproduced by the Vitra Design Museum. It costs $335.00
Below are some imitations from
whiteonwhite. I cannot link the pictures because of their strange website. But worth taking a look at if unlicensed reproductions do not bother you.

This is $125.00
Other clocks from whiteonwhite, all George Nelsons reproductions:

$125.00

$100.00

$100.00

$175.00

$150.00

$150.00