For now these are the ones that come to my mind...I don't know if this is what you're looking for, it depends too on what do you want to say to a friend.
Un amico è così - Laura Pausini
Un nuovo amico (or "Per un amico in più") - Cocciante
Che amica che sei- Giorgia
Una donna per amico- battisti
Amico- Renato Zero
L'amico è - baldan bembo (or something like that)
Se tornerai - 883
Io ci sarò - 883
"-Please tell me you're going to appeal to my humanity..."
"-Actually, I'm planning to threaten you."
"Well, if you'll excuse me, I have work to do. Evil plots don't just make themselves, you know!"