The documentation is greatly in need of a "quickstart" guide or an introductory page that's less detailed and more coherent than the Usage page.
It took me a long time to understand the usage of the template tag and the filter and when to use each. I think the documentation should contain a very basic example of using the thumbnail template tag and a basic example of using THUMBNAIL_ALIASES and the thumbnail_url template filter.
More importantly an introduction explaining the features available (without great detail) would be helpful as an introduction. I scrolled over the pre-generation section at first and didn't even realize it was a feature for a while.
I may turn this issue into a pull request if I get the time/willpower to make a more concrete suggestion.
I really liked the simplicity of the project once I figured out the features available. I think the documentation should reflect this simplicity where possible.
You're totally right, Trey. Any documentation pull requests would be definitely appreciated ;)