Open3DMap (O3DM) should become a 3D general model repository that links the 3D models of the public infrastructure (city furnitures, nature, buildings, ...) against the OpenStreetMap Object IDs. It was original planed as GSOC project in 2011 but unfortunately not accepted.
If you just wan't to upload 3D building, see OpenBuildingModels!
Current state: PLANNING
- Names come from places that doesn't exist in reality (valhalla, zion, babylon, magrathea, ..)
Collect and provide 3D models for OSM objects. Allow fine grade participation (request, offer photos, develop models in different development stages, derive specific versions/styles/..., discuss/report problems ) and maximum re-usability of the provided modeling work.
- OSM: link to single OSM objects (multiple!)
- OSM: link to OSM tags(multiple!)
- models: scale, placement, OSM tag triggers, countries
- models: adaptive model attributes (e.g. allow colour=* tag to be applied to the model)
- models: night mode, 3D printing,
- OSM: isolate possible tag combinations, countries
- collada: geometry, materials, ext. textures, animations, interaction
- API: get list of tags for all available models, get model for specific tag combinations,
- dumps: all models+textures, preprocessed model picking/placement/orientation
- Blender: Offer plugin that allows upload and checks for necessary metadata
- gallery: webgl interactive preview, thumbnail creation
- OSM,models: history on how the photos, metadata and models change during time
- Community: vote,discuss and help on the modeling process
- how to deal with multiple models per tag?
- how to deal with 'dirty' OSM tags as opperator=Deutsche Post, Deutsche Post AG, ... ?
- how to deal that Collada will loose edit history of blender or sketchup? Collada just for export?
- Support which Collada version?
- how to deal with different model versions (different geometry LODs, different detailed textures, ...) ?
- application of license-mixes: photos, models+textures, model repo, OSM, combined 3D cities, rendered results? 
- how to deal with legal problems of copyrighted real world objects  or different problems like prohibit photos ?
- how to avoid any security issues to to UGC in connected ?
- how to deal with privacy/copyright issues at distributed models?
- possible partners like wikipedia (single objects models), shapeways (3D repo), sketchup (3D repo)?
- how to deal with "fill" 3D models, like small buildings for landuse=allotments?
- how to deal with broken links OSM object ID<->O3DM model?
- how to deal with fun submissions and destructive vandalism?
- how to align models for line OSM ways, say a specific artistic wall, pipelines, ...?
- how to deal with privacy on the published photos (faces, vehicle plates, ...)?
- how to deal with commercial model designers and mass imports?
- use GeoDjango
- use Collada 3D format
- add XML manifest
- Blender 3D BLAM
- Google 3D Warehouse similar but properitary and only direct Geoposition
- Blender 3D repository
- Blender 3D repository
- Blender material repository
- Mediagobblin 3D gallery for thingiverse
- OpenSceneryX a X-Plane object library but non commercial only
- Berlin 3D model
- Valve and Blender
- Flightgear Scenery Website a library of GPL licensed 3d models used in flightgear flight simulator