Twitter corpus for Sentiment Analysis from a class (cs224n)at Stanford.
Class page:
https://sites.google.com/site/twittersentimenthelp/for-researchers#Where_is_the_Tweet_corpus_8553
http://www.stanford.edu/~alecmgo/cs224n
S. Bowman, G. Angeli, C. Potts, and C. Manning. Proceedings of the 2015 Conference on Empirical Methods in Natural Language Processing (EMNLP), Association for Computational Linguistics, (2015)