City Card - Lets you add a second Street Sign
Urbana Card - Lets you add a 3rd Sign
Metropolis Card - Lets you add a 4th Sign
Friends Sign - Contains everyone on your List
Getting the badges that require lots of Cooperation are a pain with only 5 names on a sign. I found no easy solution while participating in a Group effort for Street badges returned again and again to rotate the names on my Sign so everyone had a better chance at the badges. I sure could have benefitted from one or more Upgrades like these!