Finally, I'm keeping maybe 20% of what I take. The other 80% are being deleted.
Shooting in RAW takes up enormous amounts of space.
Because I like to keep my entire Aperture library on my laptop, I really have to watch disk space. For a time, I was floating over 200GB for my library until I forced myself to spend 20m a day for a few weeks culling. I'm still at 180GB but rate of disk space consumption of the library has slowed down significantly.
I try to keep 10% of my shots or less. These days, I only keep "high sentimental value" photos (regardless of how well they came out) and shots I'd consider putting into a printed album or on the wall. It means throwing out a lot of otherwise good pictures.
And now that Apple finally introduced "unofficial" support for Fuji's EXR sensors (it only took 2 years :( ), I've been shooting RAW on my X10, which are basically 18MB for 6MP images (it's complicated, there's pixel binning and other stuff going on, so the files are inordinately large).
Going RAW was actually a bit of a godsend - I was a digital hoarder that kept 80% of my files. It wasn't until I came to grips with the fact that I really only do look at 10% of them that I forced myself to overcome my hoarding mentality and start culling.
--sidebar--
I now use a USB gamepad to do my flagging for deletion on large photosets. I use a $5 app in the Mac App Store called Joystick mapper, and have mapped key operations to the game pad's buttons. If you're the console gamer type, you'll find yourself going through a set incredibly quickly by using a gamepad instead of mouse/touchpad plus keyboard.