We report about a project which brings together Natural Language Processing and eLearning. One of the functionalities developed within this project is the possibility to annotate learning objects semi-automatically with keywords. To this end, a keyword extractor has been created which is able to handle documents in 8 languages. The approach employed is based on a linguistic processing step which is followed by a filtering step of candidate keywords and their subsequent ranking based on frequency criteria. Three tests have been carried out to provide a rough evaluation of the performance of the tool, to measure inter annotator agreement in order to determine the complexity of the task and to evaluate the acceptance of the proposed keywords by users.