EU members do not need a passport for EU countries and most European non-EU countries. I am told that non-EU members should check the visa requirements for each individual country. Entering the USA requires a visa. Germans and others get it at the first destination airport, make sure you get the green form. Bring a pen. Beginning in 2004, the US can't rush fast enough to turn their teetering democracy into a police state and demand fingerprints and other degrading procedures; for me that means I will not visit the US anymore. If I want to visit a police state I can at least pick one that is nice about it.
The immigration officer will ask for your U.S. address, give him one even if you only stay the first night there. On the customs form, declare food (fruit, sandwiches, anything) correctly, they are very strict about this. You will have to check you baggage at the first airport even if you have a domestic connection flight. By all means avoid New York's JFK airport, it has never worked and never will. Once my non-stop Delta flight made a stop in JFK and promptly got stuck in the take-off line for four hours. I was lucky.
Beware of Tokyo. Most countries have a baggage weight limit of 36 kg. Japan has a weight limit of 20 kg. Easy to get in, extremely expensive to get out. I once paid $280.
If you buy parts during the trip, think hard before trying to smuggle them past customs back home. I have once imported a bicycle frame, and the customs officers knew precisely what kinds of frames Cannondale makes and what they cost, they had all the catalogues. They do not believe shop receipts. You wouldn't believe some of the things I have seen in the customs offices. I am really glad that I properly declared that frame...
see also article on "good & bad air lines"
