The Brothers Brick is an awesome site.They are well respected around the world.
A recent Brothers Brick post include Dablackcat's Shamgar Assault Platform.
"The Shamgar is an interchangeable weapons platform represents the latest in 2154 walker technology. Attachments include a 50 cal anti-infantry gun, Mortar launcher, Grenade launcher, and experimental rail gun. Used extensively in Jungle campaigns, soldiers have learned to rely on its hardiness. "They just don't make em' like this anymore" remarks Sargent Reynolds. "Gimme a couple of Shams an' my boys and I can take any d*** base out there.
More of his Shamgar pictures at http://www.flickr.com/photos/33465810@N06/4954777912/lightbox/
Dablackcat's Flickr page is http://www.flickr.com/photos/33465810@N06/
While we are thinking military and mech, they also highlighted Fedde's mono-track tank killer.
Lots of good ideas there!
More Flickr photos at: http://www.flickr.com/photos/dragon55/4953512780/
Brothers Brick postings at: http://www.brothers-brick.com/
Lots of great ideas, info, and pics. Updated often, so you should regularly check them out!