There are many places in Rome that sell gelato. You have the chains and then there are little places like Gelateria del Teatro.
I read about this place on Moscerina's blog back when I was still living in L.A.
She loves this place and so do I.
It's tiny. Service can be slow. However, they use fresh ingredients. The gelato is made on-site and their prices are similar to the generic chains (2 euros for a small).
The blood orange made from Sicilian oranges is in season for a few weeks. It will take every bit of will power I have for me not to walk over there every day for a cup.
It's a little hard to find, located on a side street off Via dei Coronari a few blocks east of Sant' Angelo Bridge.
Gelateria del Teatro
Via di San Simone 70
06 454 74880