Lexos is an online tool that enables you to "scrub" (clean) your text(s), cut a text(s) into various size chunks, manage chunks and chunk sets, and choose from a suite of analysis tools for investigating those texts. Functionality includes building dendrograms, making graphs of rolling averages of word frequencies or ratios of words or letters, and playing with visualizations of word frequencies including word clouds and bubble visualizations. To facilitate subsequent text mining analyses beyond the scope of this site, users can also transpose and download their matrices of word counts or relative proportions as comma- or tab-separated files (.csv, .tsv).
Lexos is part of the Lexomics Project (http://wheatoncollege.edu/lexomics/) and partially replaces the earlier Lexomics tools. See the Bamboo DiRT entry from Lexomics.