Take fewer, better photos.
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.
10 photos of an event or place will do. 500 or 1000 are not necessary, even if you do it for the "memories". If the memories where worthwhile, a few pictures can evoke them just fine. If they were not, one million pictures wouldn't help.
>My daughter takes photos of her pets all the time, her iPhone is full all the time. They aren't great photos and they are highly repetitive but they are important to her.
Well, teach her how to keep the best photos too.
Take more and keep only the good ones would be a more reasonable strategy.
It drives my wife insane when I buy a professionally taken and professionally printed postcard for a buck instead of trying my hand at cruddy homemade pix, then again I get the last laugh because I'm having more fun and get more memories out of the experience...
Obviously if you are a pro or semi pro photographer or serious wanna be, you have to look at that as a job and disregard my suggestion. However if you can't experience life because of your "job" you should still find some way to experience life at an alternative time and place. Like if you miss one sister's wedding because you were there but were a photographer instead of a sibling, try to avoid being a photographer at the other sisters wedding or whatever, so at least you get the experience one time instead of missing out on both. Life moves fast, don't miss out.
But your point is definitely valid. With concerts probably being the worst example of this. It's depressing how many people are just staring into their screen trying to capture the moment, instead of experiencing it.
Also, auto bracketing for HDR (3 pictures per shot normally), RAW+JPEG and continuous shot modes all tend to generate a lot to store.