Here is an application of parse trees: sentiment analysis with recursive neural networks based on how components of the parse tree combine to create the overall meaning.<p><a href="http:&#x2F;&#x2F;nlp.stanford.edu&#x2F;~socherr&#x2F;EMNLP2013_RNTN.pdf" rel="nofollow">http:&#x2F;&#x2F;nlp.stanford.edu&#x2F;~socherr&#x2F;EMNLP2013_RNTN.pdf</a><p>They are useful as a preprocessing step for a lot of downstream NLP tasks.  It shouldn&#x27;t be hard to find more papers that take advantage of the tree structure of language.