Online automated translators include Babel Fish, Google Translate, Bing Translator and the European Union's IATE. Thus far, the reports are that none of the automated translators are very good.
So that leaves finding a competent bilingual person to do the translation. I've had success finding translators by calling language-related organizations listed in the Encyclopedia of Associations. For translations of a phrase or sentence, I've just looked up professors on the Web sites of prestigious colleges and asked them if they would be willing to help. Most have.
If you want to hire a professional translation service, TransPerfect Translations, Inc. and Technical Language Service each have folks who can handle over 100 languages. Lionbridge is big too. Precise Translations, LLC specializes in legal translations between English and Spanish, French and Italian (email@example.com).
Patents: Patent translation is a specialty within the translation field. There are three types of patent translation: machine translation, machine-assisted translation and manual translation done entirely by a translator. Machine translation is relatively affordable, while manual is generally expensive.
Research Tip: Before hiring a translation service, check the INPADOC and/or Derwent patent families to see if a translation of the patent might be available in English from the USPTO, the EPO, or another English language register (see the "Families" of the Patents-U.S. entry).
Services that sell machine translations of patents include Paterra and Reedfax (800-422-1337). Machine-assisted translations are available from GLTaC. LexisNexis, Rising Sun Communications and Thomson Innovation provide machine-assisted translations of Japanese patents.
Manual translation services include Transperfect, McElroy Translation, Idem Translations, Thomson Innovation and Global Language Solutions. For more, see the list of Translation Services posted by the Patent Information Users Group.