Before, your options for skipping the line at the Colosseum were as follows. First, you could go to the ticket desk at the forum or Palatine hill to get your combined Colosseum/forum/Palatine ticket; although this usually worked, it wasn't always foolproof (when friends visited this spring, we went to the Palatine window at noon and still had to wait for a half an hour). Second, could go through a third-party ticket-sales service online, which added a hefty booking fee. Or, third, you could book a tour with a reputable tour company (still something I recommend, since fully appreciating the scandalous, salacious stories behind Rome's ancient ruins can be tough on your own).
But now? It's even easier. Just go to Pierreci's new ticket booking portal for the Colosseum, scroll down to where it says "Purchase your ticket," and choose your option—online or (whooooa) by iPhone. (For the iPhone option, you have to download Pierreci's app).
Once you've reserved, you can either jot down the code and bring it to the reservation desk, or print your ticket off yourself. Either way, you don't have to stand in that absurd line wrapping around Rome's most depressing most popular sight.
It's €1.50 extra, per person, to reserve your ticket. The ticket itself is the same €12 combo job (forum, Palatine and Colosseum) that they've had for a couple of years now.
As an aside, Pierreci's new website is really, really slick. Is this a sign that Rome's tourism is emerging from the Dark Ages?