Sketchfab is the perfect tool for 3D modelers and 2D artists. You can upload your own models or view thousands of others online with full 3D viewing. That includes camera rotation, shading options, and other tools to make it possible to show off your favorite work on other websites and blogs. Here's an example!
As you can see there are a ton of talented artists on here from all skill levels working both low-poly and high detail. It's a great place to get inspiration for your own 3D models since you can twist and turn the model to see the fine details including the wireframe. There are a ton of models to download and analyze in your 3D program of choice as well! The site supports 28 different file formats.
The Perfect Reference
The other awesome use for a system like Sketchfab is for 2D drawing references! There are a huge library of props, characters, and settings which can be manipulated into just the right place. It's one thing to be able to look up a reference for a guitar, but another entirely to be able to position it in 3D space where a character might be holding it, or have it leaning up against a wall.
The content on the site is of course limited to what users have uploaded, so more obscure settings, objects, and people/characters will be far less common. For general props and reference though, Sketchfab is the perfect tool!