Replying to Aperture and iPhoto libraries a HUGE waste of space?

I picked up a Macbook Pro not too long go, and since then I've pretty much been on a binge of application installing and playing around. As a result, I noticed my drive begin to fill up pretty quickly.

I decided to install Disk Inventory X to track down what was taking up all my drive space. To my surprise, the biggest problem wasn't a plethora of small stupid apps. They take space, but not as much as I'd thought.

The biggest offenders were my Aperture and iPhoto libraries at 13gigs and 5gigs, respectively. Is there a way to delete these? Or is there a way to have them just go through and access my pictures where I've stored them? I see no need to have multiple versions of my photo library, and as someone who takes a lot of pictures I won't have the space.

I did get an external drive, but I'd still rather not waste unnecessary internal drive space.

Sparknotes: Read the last two paragraphs. Thank you!