#15189037 on the list of things your cell phone can do: Become your personal filing cabinet away from home. All of those measurements and model numbers you can never remember when you're out shopping? Take a second to jot them all in your phone's notes application. Here's a few ideas to get you started.

Here are the numbers we've decided to store in our phone. But if you have a great cell phone note reminder, tell us in the comments!
The Model Number of Your Printer Cartridge
You might not be looking to stock up on printer ink. But if you find an "oh-my-gosh-I-can't-miss-this-price" sale, you'll be glad you know for sure which cartridges to grab.
Air Filter Measurements
This is the first number we decided to store. A few seconds typing out our air filter measurements sure beats having to make several trips to the hardware store wondering if your central air fits a 12x25x1 filter or a 14x24x1 filter.
Your Credit Card Information
No, not all of it. But you should definitely make a note of the phone number that's printed on your credit card to report it lost or stolen, plus any additional info like the name on the card (if you've recently changed names) and the zip code it's associated with. Hide it all in a phony contact--like your Chase Bank credit card info under "Ken Chase."
Room Measurements
After searching for the perfect rug, you finally find "the one" hiding in a dusty thrift store. Lug that shag dream home in confidence knowing you've checked that it fits perfectly in the room. And before you start the hunt for any specifics—curtains or bar stools—make notes of your window and bar measurements, too.
Types of Lightbulbs
This one's easy if all you ever buy are standard bulbs. But if you have to replace outdoor flood lights, car headlights or any other kind of bulb, you might save some time by jotting down the model numbers for each in your cell phone.
(Inside image: Flickr user Jamison Wieser under license from Creative Commons)

Shaw's Original Fir...
Also useful measurements for any member of the family whom you might be needing to buy clothes for.
I have a LOT of health problems, and every time I'm shunted off to a new specialist, they always ask for my list of medications with dosages and # of times per day I take them, and also lists of surgeries, previous illnesses (gastric conditions, cancers, etc). It's easy to forget some of then, so I keep a note that tells me all the pertinent info, so I can just transcribe it.
@JMD: I hadn't thought of that! Good idea for buying clothes for my dad, as I never can remember his pants size (he loves getting clothes. No, seriously!)
Put your ICE information on your phone's lock screen.
A lot of people I know put it on the home screen of their phone, but if you're in an accident and incapacitated, how is someone supposed to access your ICE info when your phone is password protected?????
I have an android phone, and one of things I did was create a folder on my sdcard called .info - the . in the front allows it to be hidden when using file explorer/managers, and can only be seen if a setting to show hide fields are set. I put the important info there.
I keep my hair colour number as well as window measurements in case I come across the perfect curtains one day. :)
If you have medical conditions and/or take a bunch of meds, get a MedAlert card and, if you are willing, bracelet or pendant. All of your medical information is available, as are your doctors' contact info and emergency contacts. Paramedics are trained to look for these bracelets, which have unique ID numbers and phone numbers.
Great idea to store the phone number of the credit card companies on the cell phone.
I have a list in my iPhone Notes of all the last dates I changed various things, so I know when to change them again (furnace filter, smoke detector batteries, fish tank filter, etc). I'm definitely going to add the furnace filter measurement to my list though, since I can NEVER remember it when I'm at the store!
The lengths of the dining room and kitchen tables for purchasing tablecloths.