i-phatso

I bought a 120Gb drive for my macbook a few months ago and it is already getting full. Part of this has been down to my keeping everything that I take. And since starting blip, I've managed to take about 18,000 photographs... So in quiet moments of late, I've been going through my i-photo library deleting all my rubbish photos. I've deleted about 2000 but it's slow going. I also tried something called iphoto diet today - but it only saved around 1Gb of space. Anyone got any tips for how to free up space on a mac? or shrink i-photo?