These links are to free 3d meshes. By free, I mean free as in libre. These meshes are publicly licensed in such a way that you can use them in your own projects without explicit permission.
If the license says "<popular license>-like", then the author does not specifically use that license, but in my opinion, the license is similar. You should check the actual license to make sure that it is suitable for your project.
Site: Reiner's Tilesets License: (public domain)-like. No attribution or other requirements necessary. Notes: This site has mostly isographic tiles and sprites, not 3d meshes. However, there is an area dedicated to 3d meshes. Site: Kator Legaz 3D Models License: Creative Commons Attribution 3.0 Notes: The meshes on this site are all licensed individually. All of them that I previewed were licensed under CC By 3.0. You should double-check that whatever you download is also licensed as such, or that you can otherwise use it in your project. You have to actually click a button saying that you agree to the license just to download and view a mesh. However, all you are agreeing to is the free license that you are being given. It doesn't make much sense. You have no obligations if you don't use the license. Site: Free Dragon Head License: Attribution Notes: This isn't a site. It is just one mesh by some guy. I thought it was pretty cool. Good, free meshes are pretty rare, so I'm linking to this one. Site: Worldforge Media repository License: GPL Notes: There aren't any preview pictures that accompany this media. You can setup and test the worldforge client, and see what media they have to offer. Or you can view the screenshots and figure out which model goes where. Site: Blender for Architecture License: Varies. Mostly GPL or CC-BY-SA. Notes: Mostly modern furniture. Site: Scopia's Resources License: Creative Commons Attribution 3.0-like Notes: Mostly modern, urban stuff. Buildings, furniture, plants, and more.
Site: The Official Blender Model Repository License: free for personal or commercial use Notes: The models on this website are submitted by various people, not necessarily affiliated with the site in any way. Most of the models on this site are probably GPL compatible. The website itself, however, has some odd terms. You have to be the age of consent, for example. The website terms are probably not legally enforcable in most jurisdictions. You are required to agree to the terms in order to use the website. Perhaps you will not have to agree if you never see them, as they are hidden. You should think critically whether you can use these models in your project.