Another project using this library :)
I've added a wrapper around your library for projects using the Arduino SDK:
https://github.com/embeddedartistry/arduino-printf
Still my favorite printf library!
modm.io is also using this library, albeit with some hacky hacks to disable the native floating point functions on AVR and use the optimized (fixed options) routines from avr-libc.
At least for our use-case it would've been more advantageous to have a more modular internal API, (we use the internal "static" functions _ntoa_long_long, _etoa etc too), to allow for a more custom printf build. However, that may not be a universal requirement 😛.
I just integrated this library to https://github.com/vhelin/wla-dx/issues/273 for the implementation of snprintf() - I hope this is ok. I had to modify the code a little bit to make this library ANSI C90 compatible...