The Real Paper Tank: Fake tanks were built by many of the nations involved in WW2. Local craftsmen would obtain whatever supplies were available to construct them (often plywood with a tree for a cannon). These were used to trick enemy troops and command, and at times they were placed as a trap. Units moving forward to engage the "Fake Tanks" would be flanked from another direction. Not much information available as to their effectiveness.
 
The German Panzer Holhe (or Russian Maskirovka) - commonly refered to as a "Paper Tank" (or "Fake Tank"), produces a single, unattached medium tank regiment. Although it is often the subject of jokes, the Paper Tank does actually have some practical applications in online mulitplayer gameplay. Annoy your enemies by stealing their cities and destroying their tech buildings, or even blocking their retreat. Possibly the most powerful use is a technique we'll call the....

Let's see what the community thinks about which upgrade to get first for your Japanese mortars. First Upgrade? - Japanese Mortars

Axis and Allies RTS - Rocket Trucks - We have to admit, we kind of like them, but thats about the only reason to build them in online play, except for maybe "They look cool!". You always have to consider if there are other regiments that might be more effective for the cost. In this case, that would be Russian arty tanks or Russian Armored Rocket Trucks. Both of these armor regiments have them same support vehicles, so it basically comes down to the Rocket Truck vs ISU-152. Although they both claim to have the same recharge time, the rocket truck has always seemed slower to reload than the arty tank. The most glaring differences are below.
 

health = 225	health = 330
defense = 2	defense = 5
range = 25	range = 44

See www.axis-and-allies.com/russian-rocket-truck-halftrack-regiment-ww2-rts.html
See www.axis-and-allies.com/russian-rocket-truck-armor-regiment-ww2-rts.html
See www.axis-and-allies.com/artillery-arty-tank-armor-regiment-ww2-rts.html