I always pack my computer and a puzzle book for entertainment. Sometimes I even bring a book or magazines to read. Toiletries are important to me because I don't like their items. So as far as toiletries go I pack my favorite toothpaste, toothbrush, hair brush, body wash, and shampoo and conditioner. As far as clothing goes I always carry extra undergarments just in case I have to stay longer then planned, PJ bottoms, socks, and slippers. The last thing I pack are snacks such as crackers, chips, cookies, or candy for comfort food when I am allowed to eat. If you know that you will be on a special diet such as clears or NPO (at any time) don't bring it because you will be tempted to munch on them when you get hungry. I live far from the hospital that I like so it takes a long time for family to visit me so I always pack alot just in case. If you live close to your hospital and your family can visit everyday then you wont need as much. Its all a matter of personal opinion.
Oh I forgot to mention that I over pack for everything from sleep overs, school trips, even international travels. Ive been doing this since I was little so I do over pack for hospitals too.

Make sure you bring chargers for technology items. Try to bring fewer rather than more items. Remember that there is no secure storage in your hospital room. If you are going to be out of the room for a procedure, then most hospitals don't have a way to lock up your valuables. So either make sure you have a person there to keep an eye on your things, or leave things at home.

For my husband's last stay, I brought him his phone and laptop, a book, and the important ID from his wallet (driver's license, medical cards, and one ATM card). I left the rest of the stuff at home, and then put the ID and things into a plastic bag in his shoe, so it was out of site and put away and not obvious. I brought him some hard candy to suck on and 2 pair of PJ's from home and some slippers. I brought him his pillow and a fleece blanket to keep him warm and feeling cozy. Whatever makes you feel comfortable, bring that.

iPod with sound-canceling headphones! It blocked out some of the industrial sounds of the hospital. Also, my blue stuffed octopus kept me company (and had people laughing, as he sat on my IV pole when I did my laps around the floor!) [The octopus became my totem animal during chemo. I'm convinced he saved my life!]

I also brought a cell phone case that I could velcro to my bed side rails - keeping my phone in easy reach.

Check if you are allowed regular chargers, or may only use battery chargers for your electronics.

I used their pj's - you don't need to get your own stuff messed up. Bring your own robe, however, as that makes you feel more human when you sit up or wander the halls.

cell phone + charger
toothbrush, toothpaste,deodorant, hair brush, soap
flip flops (comfy to go to bathroom/shower)
magazines-few
underwear-few
any copies of Cat scans etc.

Slippers, a quilt and a IPOD. Hospitals are so darn cold.....Brrrrrr....

My hospital is awesome. I found the bed comfortable. The wasnt much noise coming from outside of the room. I had my own thermostat so if I was hot or a little too cold I could set it to my liking. My family brought my laptop & that's all I needed lol. I watched a little TV, which I dont watch much of anyway. I loved the food, it was awesome even if it was a wee bit bland. Their toiletries were nice too..pretty cool actually. They had a spray on soap that you just wiped away. They also gave me a pair of mint color warm socks & when I ran out of clean undies, they gave me a pair. They were soft & stretchy. Anyhow, I had no complaints & missed the room after going home. It was so quiet & dark that I was relaxed the whole time. No hubby, dogs, or hyper child. *sigh* It was like a mini vacation. BTW, I was in there due to hematomas in my throat that the anesthesiologist caused when intubing me Mondays & Fridays for 4 weeks. However, the only thing I always wish for, is my own pillows. Hospital pillows always slide off. :)

Florida Hospital Waterman is THEE best!

Earplugs! Slept really good due to them, scared the nurse cause I didn't move 2 times when she came in and she had to touch my foot to wake me up. She was relieved to see me take out the earplugs and told me what a good idea they were.

Definitely your own PJ's, undies, extra socks, a blanket and I always bring my own pillow. Everyone has pretty much covered everything above. I also bought baby wipes - you can use them on your arms, legs, anywhere for a quick freshening. Colgate makes Wisp which is a small mini-brush for your teeth where you can just use it and don't have to spit out - another small refresher.

I brought my ipod and my laptop. I listened to my ipod nightly and it helped me relax when I was anxious or had trouble sleeping. My laptop I used only a couple of times but I think if I didn't bring it I would have missed it.
Definitely: pjs, undies, socks, slippers or comfy shoes, baby wipes are awesome, cell phone and charger, charger for laptop or ipod too.
Good luck!