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
This explains several ways to use consistent colors across plots (same way works with scales). However, the easy way explained in one of the alternative answers does not seem to work for some versions of R/ggplot2. Opting for the accepted answer always works though.
A collection of index based algorithms for comparison purposes. Also contains RStarTrees for indexing and the DBSCAN algorithm. Yet, this library is not intended as a library and really is complicated to use (see http://elki.dbs.ifi.lmu.de/wiki/HowTo/InvokingELKIFromJava).