Well, this may not fall into the category of things you can pack up and send them, but I found this was essential:
1. Before they leave for college, teach them how to locate all the serial numbers, model numbers, etc., of all their "stuff" (iPads, laptops, computers, cell phones, iPods, electronics, musical instruments, bikes, etc) and record those somewhere. My son took photos of his serial numbers and emailed them to me, and I keep a copy with our documents (in a small safe). Teach them that when they get a new electronic item they must inform you of the serial number and other info. I have yet to hear of a college kid that hasn't had something lost, stolen, or just dropped and broken.
2. Teach them about property insurance (renter's insurance, or your homeowner's insurance). Make sure they know the insurance company's contact info, and what is insured and what is not. You should review that kind of thing yourself, with your insurance company. Make sure their expensive stuff is insured, and if they add something to their inventory, how to inform you and the insurance company. Tell your insurance company about the location of anything you own (like if your student is taking your laptop or computer) and inform them of your student's address. They should know how to talk with the insurance company and should make some of these calls themselves.
3. If they'll be driving, make sure they know who your (or their) auto insurance company is, where the policy info is in the car, who to call in case of an accident, what immediate steps to take at the scene of the accident, etc.
4. Do you have roadside assistance through your cell phone carrier or AAA or anything, for getting locked out or having a flat tire, etc? Make sure your college kid knows the rules of the program, who to call, etc.
5. Before they leave, photocopy everything they have in the form of ID (student ID, driver's license, credit cards, library cards, store cards, membership cards, etc) and keep a copy in a secure place.
6. If they'll be driving, consider an emergency bag in the trunk of the car. I don't mean jumper cables. I packed a large (2.5 gallon) ziplock bag with a pair of warm gloves, a wool hat, a flashlight and batteries, those hand warmers you can get at camping stores, socks, a notebook and pencil, and some food items like granola bars, dried fruits, etc. This bag was only to be opened in the event of breaking down or running out of gas or getting stranded.
7. Have a linked bank account. Nothing is more frustrating than trying to figure out how to mail emergency money or get to Western Union, etc. Being able to hop online and transfer that $20 for emergency gas money from your account to theirs is so helpful. And you can monitor (if you both decide this is important) where the money goes. If they ask for money for gas or food, and the linked account shows that they blew all their money at the shoe store or on iTunes, you will be able to take appropriate action. Even if your student is careful with spending and the monitoring is not necessary, being able to transfer quick funds in the event of an emergency is nice.
8. If they have something other than a pay as you go phone or any cheap phone, consider the replacement or accident insurance through your cell phone carrier.
9. If your student will be doing any traveling (spring breaks, or school trips, going to visit a roommate's family over a holiday, or study programs) and will be taking their debit card, teach them to notify the bank about any extended trips (time or distance). Banks these days often freeze your account if they notice unusual activity. I was in line at Target with my son buying him bedding, printer paper, and cleaning supplies for his college experience when the cashier informed me that my card was declined. I called the bank and they told me they noticed that my card was being used in an unusual location (12 hours away from my home). Of course it was all straightened out immediately, but now we know if we're flying somewhere or traveling somewhere to let the bank know where to expect our cards to be used. Also teach your student that if their debit or credit card is lost, to call the bank the second they realize it. That means they have to know the name of bank.
10. I sent my son with a thin accordion-type folder, labeled, so he could store his paperwork. Make pockets for credit card statements, receipts for big purchases, school records, health records etc. I know a lot of stuff is online these days, but still you're bound to get the occasional paper statement, or bill, or warranty, or instructions, and having a place to put it already helps keep things organized.
11. If your student takes any prescription medications, they should have a printed list of the names (so many take prescriptions and just know that they take the little round pill in the morning and the orange square thing with meals, etc. I'm not talking about being irresponsible and taking pills they shouldn't, but legitimate prescriptions: the names can be difficult to remember), and they should know which pharmacy prescribes them. If your student is going far away, it's helpful to know which pharmacies are in the town where the college is, like a national chain pharmacy (CVS, or Target, etc) and have the prescriptions filled at the chain in your location. That way, if they run out of their medication or lose the bottle, they can go to the local chain near their school and get help.
Knowledge about all these things will alleviate a lot of headaches, in college and beyond.