Thingiverse is dedicated (only?) to .stl files
(Thingiverse also had “thingiview”, 3D preview of stl model. WebGL enabled browser needed for that.)
3D warehouse is (only?) for .skp files
TF3DM is for all 3D files. TinyUpload is great for general file hosting.
I found those 2 links, there are plenty more hosts to choose from: