Image stabilization helps. But just because you don't have a tripod doesn't mean you can't improvise one.
I've posted this pic before, but what I didn't say was that I improvised not having a tripod, by resting the camera on... a trash can. Yes - my favorite picture from last year was taken by setting the camera down on a dirty bin. The only change I needed to make when I got home was a few degree's straightening in photoshop.
Oh and it's a 30s exposure too.