'cleaning' my mac

Spent most of the afternoon and evening 'weeding' out unnecessary files in my MacBook. Just found out I only have about 10GB of storage left due to more than 15,000 pics in my Aperture library, and a few .dmgs I left in the harddrive after installing new applications. I recovered about 90GB of space afterwards, then uploaded a few CFs of pics from our last two travels, which again occupied 10GB of precious storage space... if this goes on, I really need to put serious thought in buying another terabyte of external harddrive. (Or better yet, get me an iMac, of course, with a bigger storage.)