This paper gives an overview on crowdsourcing and co-curation practices in virtual museums. Engaged nonprofessionals and specialists support curators in creating digital 2D or 3D exhibits, exhibitions and tour planning and in the enhancement of metadata using the Virtual Museum and Cultural Object Exchange Format (ViMCOX). ViMCOX is based on international Lightweight Information Describing Objects (LIDO) v1.0 metadata standard, provides the semantic structure of exhibitions and complete museums and includes new features, such as room and outdoor design, interactions with artwork, path planning and dissemination. Various application examples show the impact of crowdsourcing, co-creation and cocuration on the digitalization of expositions in classical museums and on the creation of virtual museums. The case studies are devoted to restoring lost or damaged artwork by the GermanJewish sculptor Leopold Fleischhacker, high-quality 3D shapes and Armenian cross stones. Finally, the paper reports on an evaluation in the field of usability, user interfaces and the crowd's willingness to undertake various co-curation subtasks.