It seems that such corpora are best discussed at Linguistics.SE and questions about specific NLP frameworks such as NLTK are best reserved for SO. And yet these questions have been asked:
- Building a Sentiment Analysis Dictionary for a Non-English Language [closed]
- Database with English words with grammatical classification?
- American English SMS Text Message Corpora
I can see how finding existing corpora could be on topic here, but I'm not sure questions about how to construct a sentiment dictionary should be on topic. What do you think?