gdbTags is a visual means of displaying the book categories that are available on Greydoorbooks.
The way it works is that the bigger the type, the greater the number of books in that category. You can click on a category name to go to its listing. Please note that this list is still being developed in the beta phase, so if you see any bugs, let us know!
Greydoorbooks is also working on a member driven tagging system which will give you the ability to sub-categorise books.
We'll let you know when more details are available.