Recently Google announced a Linux version of its Desktop. It allows to search in local files and internet from one interface. Google Desktop supports many types of files such documents, images, music etc (it takes information from service data I guess). Moreover, you can make a search in your search history (sounds funny – search in the search, but I use that feature often) and GMail. Full list of features is available here.
Google Desktop is multilingual application. So, you may use it with your native language. Google Desktop for Linux can be downloaded from here.