Well, you may know some of this already, but...
As far as air travel goes, you might want to check out
http://www.tsa.dhs.gov/ for all the gory details of what you can't do.
One of the biggest things to watch for is bringing liquids or gels -- you are only allowed "3 oz" bottles and they must be in a "1 quart" ziplock bag.
Also, for going through security you will probably be asked to remove your shoes, so consider a pair that are easy to take on and off. Also anything with metal, like a belt -- I was very happy to have my non-metal belt with me last time.
Your electrical gear will not fit into US sockets unless you have an adaptor, plus we use an antiquated 110 vac mains circuit so you might need a voltage converter as well (though many items like laptops are rated for 100-240 volts). Hotels can sometimes provide these, but the staff will not necessarily be knowledgeable enough to give you exactly the right equipment.
Also, here's a neat "Worldwide Tipping Guide":
http://www.magellans.com/store/article/367?Args=
Don't know how accurate it is as it says you should tip in Finland, but I think it's interesting (NERD!).
