I would love to have a model library, with textures and labels kept in situe on the models, as I use a lot of repeated products, and packaging, and could do without having to reapply the labels every time.
The next step is easy. You can save your bip files in a shared folder or network drive and drop'em into your scene if needed.
Or you can save the bip file into the models folder from your resources library. Then you'll find the in edit->add geometry. But this menu has not much space.
Hope that helps.
From what I hear this will be getting some love in Keyshot 7, but for now I do exactly that. I have a folder of assets as my library, and I have added stuff to the "Add geometry" menu, but like it has been said, the list gets long quickly :)