When I was at the NOVA Open recently I did a fair amount shopping in the vendor hall. One of the cool purchases I made was a defensive bunker from Tectonic Studios. It caught my eye because it looked similar to some other GW terrain pieces but lacked the overabundance of skulls and gothic bits the tend to plague 40k scenery. The gothic stuff is cool but I've got plenty like that, and this bunker looks to have a lot of value for 40k and other games like Infinity as well. It went together well with the help of the instructions found on the Tectonic Studios website and overall I really like it.
The best part is that the top level is easily removable.
Also from Tectonic Studios, a "Tau"style objective marker.
I also recently built a fence set from Laser Cut Card and while simple, this set was really fun to build and will be great for all types of wargames.
Finally, I picked this up at the NOVA as well, it's a garbage dumpster from Bandua Wargames. I know it has the recycling symbol on it but do you really think those Ariadna trash recycle?