Our proposed "Language Grid" infrastructure supports multilingual communication by combining in new way language resources, such as machine translators, morphological analyzers, and dictionaries specific to user communities. We developed the Language Grid as a language infrastructure on the Internet. The Language Grid enables user communities to combine two or more machine translators and their community dictionaries by workflows, and to easily create new multilingual services specific to the communities. Because the quality of language services is not often defined, however, we need to confirm that the created multilingual service is really useful. We need to extend the process of general usability testing to the multilingual environment. For example, cooperation between user communities and language grid providers can significantly improve the accuracy of machine translation: it turns out that machine translations can be useful for interactive communication in the field of inter-cultural collaboration.