(Other than the obvious... snowboard jacket, snowboard pants, sweat pants/pj pants/long underwear/under armour for under your pants for warmth and cushioning, snowboard/ski socks, goggles, beanie, gloves - with liners if possible, to keep your hands warm while taking the gloves off to do things like use your cell phone, change music on mp3 player etc, snowboard boots, snowboard bindings......)
First - you need a stomp pad. The BEST new product out there is called a "Strap Pad" (I have one for each of my two snowboards). You can put your other foot in this strap on the lift, so when you go to get off, your feet stay in place and you wont eat s*** as you get off (and will be the envy of all other beginners out there). I purchased mine through Amazon.com.
Second - go buy a cheap pair of volleyball knee pads at a local sporting goods store. Even the thin ones work great. When you learn, you either fall on your knees or your butt. The knee pads will save you so much pain and help reduce the pain as you are waiting for your friends on your knees. I swear by my knee pads.
Third - the best way to stand up is by grabbing the front of your board (between each binding) with one hand, and lean forward from there.
Fourth - Before you begin to "learn" how to turn, start out by just going down the entire run on your heel (stopping the entire way), and then on your toes (facing towards the mountain slope). It will work your calves A LOT, but it's the way all snowboard instructors start their lessons.
Fifth - Keep asking questions! Use ExpertVillage and SierreSnowboard's youtube videos and study snowboarding "how to" videos. Then put it into practice!
Sixth - Don't back down. It took me 6 days on the mountain before I could actually get up to ride. As a girl, I obviously cried, trying to learn on ice/hard pack (not a good idea). But I kept getting up. This is key. Now, with 30 days on the mountain, I can ride switch easily, and can do kickers, boxes, and mini-big airs in the terrain park. Yes, I did purchase a helmet as I ventured into the park.
Hope this helps! Good luck!