I'm getting ready to give birth to my son anyday now. What are some things I need to bring to the hospital with me? (I keep feeling like I'm forgetting something)

Did you take a tour with the hospital's delivery area? They should have given you a list. If you have not and wish to, call them, it is a normal practice for women to tour the area. Then you can ask.
For labor you want soothing music, bring a selection. Candy suckers on a stick, only on a stick. Any pillow you love. If you took labor class bring anything you practiced with (except the floor mat). Reading material for your honey, TV programs tend to make a woman in labor a little crazy.
Breastfeeding bed gown if you are breastfeeding. Slippers with no-slide bottom surface. (not furry bottoms) Several underwear. Bring underwear that you imagine your grandmother wearing, huge coverall, not tiny things. You will be wearing huge pads.
A change of clothes for your little one to come home from the hospital in. They want them in hospital clothes while they are there.
You need an approved car seat before you can leave the hospital.
If you are bottle feeding, bring a couple of different nipples as kids can be fussy if they don't have mom.
You want your bathroom kit but don't make it extensive, you will not feel like putting on much make-up.
If you are breastfeeding you will NOT need nipple pads just yet. You will use them about 2 weeks out. The hospital will give you cream for your nipples. If they don't ask the doctor for some before you leave and use it.
Those are the essentials as I remember it. Labor has changed a little since I was a labor nurse, but you will do fine.
Ask questions, what are they doing and why?
Make sure they wash their hands. Make sure the doctor knows your plan and agrees with it or you talk it out.
Be fully involved with your care and your baby's care.
And Good Luck!

I wanted to add to Alicia_Honey. Don't forget your camera, at least for still shots, don't know if you want a video camera, that's more personal, but definately a camera, and a phone. Don't forget to let everyone help as much as they want, because it might not be that way as much at home.

your own pajamas.

Bring someone with you so if you forget something they can fetch. You are going to be on a gurney and squeezing. Then you are going to sleep. Then you are going to wake up eat and probably be out of there in a day or two. What is the big emergency?

of course, your pregnant you forget everything these days.lol
well, clothes, that are really comfortable,
feeding supplies,
blanket and pillows,
many different sizes of clothes for baby,
hygene producks and pads
lots of pads
conditioner
lotion
CAMERA

Just wanted to pop in and say congrats!! =)

Some chap stick might be a good idea. I know my lips were chapped after each one of mine. The hospital brand sucked..LOL

Don't worry about forgetting stuff..LOl I know it's easier said than done but trust me you will have what you need. What you don't have, don't be afraid to tell family or nurses. Good luck to you and the lil slugger!! =D

Maybe a folder or something to keep all of the paperwork in so it doesnt get all crumpled in your overnight bag.

Congrats!!!!! I see just about everything is covered with the other answers you were given. The only thing I can add is to bring something to eat for after you give birth. As soon as it was over each time when I had my kids, I was absolutely starving! The hospital might have a cookie or something for you, but you'll probably want more than that.