Photo library observations
I recently bought a new MacBook Pro and am going to be using it as my only computer. As a result I'm gradually moving my "stuff" to it. That stuff includes my iPhoto library which I'm planning on keeping on an external drive. When I copied the library from my iMac I was shocked to discover that it was over 250gb causing me re-evaluate the pictures that I've been keeping (more than 12 years of files). A photographer blog that I read (http://rockymountainjoe.tumblr.com/post/7359600885/the-10-steps-of-my-aperture-workflow-this) had noted that he had learned to zealously police his photo archive for the same reason so I am also in the process of deleting unneeded pictures and finding that there are many that really have no long term value to me. Examples include hundreds of picture of random airplanes at airports, numerous duplicate shots of food (I like food photography), duplicates due to resizing and editing, neighborhood events (4th of July parade in 2006 for example) and so on. I've already reduced the archive by a few thousand shots (10s of gb so far) and am still working on it.
I've read that Aperture is superior to iPhoto in a variety of ways including that it only keeps a single original of images. I tried to get used to using it a year or so ago but never got the hang of it and went back to iPhoto. With this physical file move I'm going to give it another shot. I had also recently found a link to a photographer site that has a few ebooks on Aperture library management which I'm going to get (http://store.rwboyer.com/). In addition I want to think through a good workflow for me which will probably primarily include not importing all shots from my Panasonic Lumix and Canon Digital Rebel and instead being selective. I may also try importing only from the my iPhone photo stream selectively instead of when I sync with iTunes. I had been shooting 95% of my shots with my iPhone but since the MBP has a SD card slot making it easier to import from the Lumix I am doing more with it. The Canon uses compact flash so I have to attach a card reader.
In general I think it is important to plan your own workflow because of the number of files that you will eventually end up with.