Roads and Crosswalks ground template - I've used these a lot over the years.
Cav's Paper Terrain 1 - Mailboxes, Dumpsters, Large Crates...
Cav's Paper Terrain 1 (grunge)
Cav's Paper Terrain 2 - Crates and Soda Machines. I used these as templates for the soda machines found in the DCU - Soder Cola "Sometimes even super-heroes get thirsty." and Zesti Cola.
I've actually switched to using some of my sons foam blocks for the crates...full sized cubes are same size as these large crates and fit in one hex. I cut one up into two stacks of 4 for the small crates.
Armored Truck Same size as the Ambulance toy my son has. Sometimes I just use the Ambulance as the Armored Truck but I used this for a campaign scenario.
AliasQT has some good stuff that can be modified to work as well...
Wall Panel Templates - I've used these to create Skyscrapper skins that can be used with the FotA set to create buildings.
AdvPack - Factory Windows & Doors - Got the idea from this
AdvPack #3 - Medieval Cottage - can be reskinned for an alternate version of a small house.
Rather than listing them individually...
Grishnakh's Custom Terrain
found this as well...a Dumpster