estrat-histogram generates ASCII histograms based on word frequency. Its author is Eric Stratmann (estrat). You can build estrat-histogram using cabal.

$ cabal install

estrat-histogram accepts text from files passed in as arguments or from standard input and outputs a histogram to standard output.

$ estrat-histogram textfile1 textfile2 foo: ######## bar: #### baz: ##

$ estrat-histogram < textfile ape: ############# dog: ####### cat: ####