Stefan Krause wrote a university assignemnt about NMRShiftDB (in German). It's available here.
You can also view the api doc for nmrshiftdb2 at http://nmrshiftdb2.sourceforge.net/api/.
The current ER diagram of the nmrshiftdb2 database is also available here.
There is an nmrshiftdb2 administrators' guide and a developers' guide. Various topics are also discussed in the nmrshiftdb2 wiki.
Various publications relating to NMRShiftDB or nmrshiftdb2 have been published.