Bare trees in Winter.  It's funny, there are all kinds of issues with this photograph (the tower in the background being one that makes me nuts, but for a photo a day, I have to let some things go), but when I view it full size, i'm still taken by the power and beauty of their structure.

"There is unrest in the forest
There is trouble with the trees
For the Maples want more sunlight
And the Oaks ignore their pleas"

-Kilmer/Rasbach (as performed by RUSH)