Although 'gelato' translates as ice cream; you just can't translate it, as Italian gelato is on another level to all other ice cream. The best ice cream shop is in none other than Monte. It's called Fatamorgana and located very near to the Cavour metro stop. Although there are lots of great ice cream shops around Rome, I think that this one is the best as the flavours are incredible and every time that I go there (which is a lot) there is another new flavour that I just have to try. Some of the flavours that I've had so far are: lemon, honey and ginger or cardamom pod with almonds or chocolate and lypsung tea or coffee, chocolate and hazelnut or pistachio with hazelnut and of course there are all the usual flavours.
A little tip: you can also ask to test a flavour by saying "posso provare" - so if you can't decide you can test them out :)