You can also checkout https://github.com/vseloved/cl-nlp. It is an NLP toolkit in Common Lisp. Vsevolod the project owner is a great guy to work with. I had contributed with some minor bug fixes, tests, documentation more than a year back, hence the mention of Vsevolod.

You could also think on the alternative lines of contributing to an open source project in NLP and building an application on top of it. Talking to any such project owner for expected sample apps might help, as they can go into that project gallery and you get to level up your skills. Hope this helps.