You want something unusual? Well,you get it.Just watch it!
In Iasi, in front of Culture Palace, the trams and the trolleys are sharing the "+" cable!
As you can see in the picture, the "+" cable is centered above the tram's track(rail), the "-" is of course the rail.
The trolleybuses use tram's "+" cable and another "-" cable, situated a little bit far than usual.  
Iasi, ex- Republic of Moldavia type trolleybus on route #41.
Photo by Catalin Ghita, whitewolfcata@yahoo.com