Given the shortage of the Babelfish on Earth, being able to understand or make yourself understood in languages other than your own can be an exceedingly difficult affair.

The Old-Fashioned Way

Firstly, it is possible to actually learn a language. This can mean sitting for many hours in a room with a book and somebody to teach you how to understand whichever language you have chosen to learn. This is an effective, but often slow method, and the modern hitchhiker often does not have three years to sit in classrooms, simply to learn how to say "Any chance of a lift to Bristol?" rather badly in local dialect.

Travel-Guides

Another option is to purchase a travel phrase-books, although this requires that you know where you are going and what language they speak when you get there. Often, a hitchhiker will only know where they *want* to go, but not where he or she will actually end up. Another problem with this is that unless the phrase-book is packaged with some kind of audio examples of the language, pronounciation can become quite an issue. For example, the often-told joke of Bill Clinton asking the waitress for a "quickie", when he actually meant to say "Quiche".

On-Line Translation

Yet another great option is the on-line translation website.
There are several of these, and they can do anything from translating a single word to very badly translating an entire web page or any arbitrary passage of text of your choosing. Never rely on one of these to be grammatically correct in any way. Another down side to using these is that you need to have some way of accessing the internet with you whenever you want to use them. Whilst you're out hitchhiking, you may have a laptop computer, a mobile phone or palm-top computer which is capable of accessing the internet, tickets to a local internet cafe or maybe you have your mini-tower PC and 19 inch monitor in your rucksack, crushing your quiche.
The best known on-line translation site is probably http://babelfish.altavista.com/ - named after, of course, the Babelfish. It is capable of translating the following Earth dialects: English, Spanish, French, German, Italian, Portuguese, Russian, Japanese, Korean, Chinese. Although you must be translating either from or to English.

If the language you want to translate from or to is not listed there, you could do worse than try Tranexp's Intertran service. This can be found at http://www.tranexp.com/InterTran.cgi and supports many more languages: Bulgarian, Croatian, Czech, Danish, Dutch, English, Filipino (Tagalog dialect), Finnish, French, German, Greek, Hungarian, Icelandic, Italian, Japanese, Norwegian, Polish, Portuguese (domestic and Brazillian dialects), Romanian, Russian, Serbian, Slovenian, Spanish (domestic and Latin American dialects), Swedish and Welsh. This service can be very slow to use, as it can take quite a long time for a computer to find what you're looking for out of all those words. Also note that you may not be able to access the site from some office network set-ups. For the technically minded, this means you need to be able to establish an outbound connection on TCP port 2000 to use the translator. Check with your firewall administrator if you can't get it to work.

Another such site can be found at http://www.freetranslation.com/
This site is fast, and offers the following languages: English, French, German, Italian, Spanish, Norwegian, and Portuguese. Much like Altavista's Babelfish, you must be translating either to or from English on this site.

If you ever happen to find yourself sitting close to an internet cafe in Poland, with no idea of anything except what a Polish internet cafe looks like and which country you are in, you would be well advised to look-up http://www.poltran.com/ which will perform translations between English and Polish or vice-versa.
This site is run by some people who make hand-held electronic translators, which can also be handy, but again, also expensive.
On their own site at http://www.ectaco.com/ it is possible to translate individual words to or from English, choosing one of the following languages: Albanian, Arabic, Bulgarian, Czech, Dutch, French, German, Greek, Hungarian, Italian, Korean, Latvian, Farsi, Polish, Portuguese, Romanian, Russian, Serbo-Croatian, Slovak, Spanish, Swedish, Turkish, Yiddish.

If you decide you'll like to learn a few phrases in a foreign language, but would rather not pay for lessons or a phrase book, you could take a look at http://www.travlang.com/languages/ which can teach you bits of many languages, such as: Afrikaans, Albanian, Amharic, Arabic, Armenian, Asturian, Azerbaijani, Basque, Bengali, Bosnian, Breton, Bulgarian, Cantonese, Catalan, Cornish, Creole, Croatian, Czech, Danish, Dagaare, Dutch, English, Esperanto, Estonian, Eurish, Farsi, Finnish, French, Frisian, Galician, Georgian, German, Greek, Gujarati, Hawaiian, Hebrew, Hindi, Hungarian, Icelandic, Ido, Bahasa Indonesian, Interlingua, Irish (Gaelic), Italian, Japanese, Korean, Latin, Latvian, Lithuanian, Luganda, Bahasa Malaysian, Mandarin, Marshallese, Norwegian, Occitan, Polish, Portuguese, Quecha, Romanian, Russian, Serbian, Sesotho, Slovak, Slovenian, Spanish, Swahili, Swedish, Tagalog (Phillipines), Taiwanese, Thai, Tswana, Turkish, Ukrainian, Vietnamese, Welsh, Wolof, Xhosa, Yiddish and Zulu.

The Fun Way

Of course, the most fun way to learn a language is to go somewhere where nobody speaks your language, and just try to pick the language up through what your hear and see. It works, afterall, that's how you learnt your language, isn't it?

Silly Translations

Finally, if you are having trouble understanding dialects such as Cockney, Redneck, Moron or Pig Latin, you can use the Rinkworks "Dialectizer" to convert text or web pages. You can find it at http://www.rinkworks.com/dialect/