As others have said,
Reds! and
Bayonets Won't Cut Coal are fantastic timelines exploring successful revolutionary movements in the US and Britain respectively. Other decent revolutionary socialist timelines include:
Wir Sind Spartakus - a timeline about a successful revolution in Germany
War of the Classes: A Gilded Age Timeline - a fantastic, but unfortunately dead, timeline exploring a revolutionary workers movement along the vein of the Paris Commune emerging in the US in the 1800's
And one day I'll write my Italian Revolution timeline... one day.