Guernica
 

It is inevitable that this would crop up as a subject. Picasso's striking 1937 piece does not appear to have been homaged frequently, probably because of its complexity, but I have found some. There has been something of a resurgence lately as the image is used in anti-Iraq war protests. Here's the original, click to enlarge.

This is a splendid cartoon from here which compliments one of my favourite Mondrian pieces here.

Another cartoon, but the intention has eluded me so far. from here.
awaiting permission Danny M. Valdez
from here

 

from here

Dr David Baker of Warwick University has  devoted a lot of energy to reworking the piece. Many of the works can be seen here. The images shown are  Deconstruction 5 and Reconstruction 10.
Iraqnica, from here.
Guernica Theatre, a photograph by Diane Greene Lent, from a site showing images from anti-Iraq war protests. From here
Guernica 2003 by Adam Strange, from here.
by Tom Moore, from here, Heath Primary School, Portlaiose, Ireland

There's some very good work here.

from here.

image 250 high to 100