How to use views hooks - specifically hook_view_data()?
Views does have complete documentation for that hook, but it's not in the most obvious place. 

If you install the Advanced Help module and go to http://mysite.com/help/views/api-tables you'll find the Describing tables to Views help page which contains extensive documentation and code samples.

You can also find the full Views' API docs at http://mysite.com/help/views/api with that module installed.

On top of that, the list of functions that implement hook_views_data() would also be worth a look. The aggregator, book and node module implementations look to be well commented at first glance.