For those lucky enough to get an iPad, you already know that the box contained the iPad, a 10w Power Brick, USB Cable, 1 page instruction manual, and the FCC information. For those who don't have theirs yet, I have a little advice on what you need to get, carry, and not carry with your iPad.
1. The extra 10w Power Cable isn't shipping until May, and the USB cord the iPad comes with isn't long enough to reach from the wall to a bed side if you have a bedside table. If you have a Macbook the extension cord that slips into the power brick it comes with works fine to give you a few extra feet.
2. Headphones. No one wants to year my Cannibal Corpse/Frank Sinatra mix at the coffee shop. The ones that came with my iPod Touch work great, including the volume control. The iPad has a built in mic already that works great, so any head phones will do.
3. Microfiber cloth. I am an oily person, and I leave my grease everywhere I go on everything I touch. It only takes an hour of me typing on my iPad to make the screen kinda cloudy. Do not use tissues, a rag, your sleeve, or anything but the softest microfiber cloth to clean the face of your iPad.
4. Bluetooth Keyboard or Keyboard Dock. I got the Bluetooth Keyboard because it wouldn't be as clunky as the dock and I could set it my lap. Before buying any of these however, make sure you've typed on the iPad for a couple hours first. I somewhat regret getting the keyboard because in only a select few situations I probably will prefer to type on-screen in landscape mode.
5. Case. Yes get a case. I haven't actually laid hands on the one from Apple so I can't comment but it looks pretty decent. Here are some other options.
http://www.quirky.com/products/30-Cloak
http://www.medgestore.com/products/ipad/
http://sfbags.com/products/ipad-cases/ipad-cases.php
http://www.hardcandycases.com/ipad-products.html
http://www.longlivebooks.com/bookforipad.html
http://www.i-luv.com
6. Bag. Something small to carry your iPad in isn't a bad idea. Most cases just offer protection from getting bumped around inside your carry-all. If you want something to just carry your iPad around in I recommend one of these three bags.
http://www.timbuk2.com/tb2/products/laptop/netbook-laptop-cases/slingshot-netbook-case
This is the one I bought. I can actually fit everything in it, including the bluetooth keyboard, but there's little room for anything else.
http://www.sfbags.com/products/muzetto/muzetto.htm
This one is expensive, particularly for guys with wives who steal their stuff. This thing is nice enough I could see a guy, gal, or a small Gerbil named Kevin carrying it.
http://www.bbpbags.com/industriesmessenger.html
For the people who don't already have a good laptop bag and need a really tough one that wears high across your back and shoulders for riding two-wheeled vehicles, this bag looks to be the best out there.
Crumpler also makes a good bag. [https://www.crumplerbags.com] They have a charming website too.
Even better are the names they gave their bags. I own one they call the "Considerable Embarrassment". I bought that one in particular because it has no external pockets and I'm always nervous someone will mess with my bag while they're standing behind me in line. Clasps and velcro for the paranoid carrier of devices.
7. Stylus & Stands. If you think you really need them.
http://www.tenonedesign.com/
They make a neat stylus for the iPod Touch that works well with my iPad. However, I've already busted the dratted thing twice. If anyone finds a sturdier place to buy a stylus that works with the iPad, let me know.
http://twelvesouth.com/
These guys just make neat stuff. Don't know that I'd get a stand but 1000 nerd points for anyone who does.