Forgive me if this states the obvious, but sometimes I am surprised by the reluctance of people I talk with to travel to Europe because of hesitancy about the language barrier. While I'm sure this applies other places too, my experience in Europe has always been fairly easy. The biggest advice I can offer is to try to learn basic phrases in the languages of the countries you go to. It isn't even so much about being able to speak them, but moreso to start an exchange that way and show that you're making the effort. Its a sign of respect, and sadly one that Americans often neglect. Once you fumble through a phrase, the common response is a smile and "I speak English." Don't start in English and expect them to speak it as well - most anyone in the US would be equally offended by someone expecting that in their language. (The difference, of course, is that we rarely do speak theirs.) When going to Italy to work the Olympics, NBC sent us a basic language phrase card that fit in your pocket. It was incredibly handy. Now you can find sheets like this online and print them yourself. They're great to check for basics like numbers or days of the week and greetings. And if nothing else, ask someone. When in Prague, I found myself completely clueless about language, so I asked the desk clerk at my hotel how to say basics like "Thank you," "please" and "I'm sorry I don't speak Czech." As I left, he stopped me to say "that was really nice of you to ask." Don't deny yourself the opportunity to experience other worlds. Just make the effort. It pays off in spades.
[apologies for blog posts before 1/2009 that are not yet updated to format]