Just some things I'd change:

1. Stop being so lax in administering certain things. That's a sizable and difficult request, as I could only imagine. The site is nice in concept, but it could use some policing so it doesn't get run down.
2. Limit some features and ease of use to registered members only. This means that if you're a guest and want to download a model, you're going to have to take the time to type in a capcha.
3. For models or packaged type items, only downloads count in the scoring system. (This is why capcha would be required for a download in #2 as it would be more difficult to easily inflate the score in an unethical manner.) Views as a score will remain for things such as images, etc. where it is appropriate.
4. "Pick of the Day" will be replaced by "Pick of the Week", since it currently appears that it is not updated daily as it is. There will also be a blog-type page highlighting a model's features and some explanation as to why ShareCG staff came to that conclusion. (We want to see a nice review done, more or less.)
5. Payment only on an award basis. (I've noticed they stopped paying now because of existing abuses.) Elgible models will be judged by the staff of ShareCG. Those that get "Pick of the week" or "Pick of the month" will get a decent award in the range of $25 to $100 dollars. This will provide an incentive to continue providing freestuff, but will not reward dumping/spamming. (The "ridiculously small returns per view" incentive model only encouraged such abuses.) I think most people would prefer quality, not quantity. Also, after being awarded, there would be a period of inelgibility.
6. The rating system would have more criteria. There would still be the 1 to 5 star overall rating. But to make more sense, there should be specifics. Other criteria would be: 3D model mesh, textures, documentation, and ease of use. The person uploading can also check whether or not such a criteria would apply to the uploaded item. (Doesn't make sense to rate textures if a model does not have them, etc.)
7. Obvious repeats of models will be removed. Having a single barstool with 20 different textures will not be allowed to be distributed as 20 different models. Instead, 19 of those will be removed. If a person wants to have 20 different textures, either package all of them with the one model or upload the different textures to the texture category where they will not inappropriately clutter the 3D listing.
8. Models could also be subcategorized by level of detail. (Not every model is intended to be hyper-realistic nor should be.) Initially this would be selected by the uploader, but could be nudged in the appropriate direction by downloaders or even modified and/or locked by staffers.

Probably more could be added, or perhaps more detail to specific points. But those are changes that I would have done. What do you think?