A rhyming dictionary is a specialist dictionary designed for use in writing poetry. In a rhyming dictionary, words are categorized into equivalence classes that consist of words which rhyme with one another. They will also typically support several different kinds of rhymes, and possibly also alliteration as well.
Because rhyming dictionaries are based on pronounciation, they are more difficult to compile that they may at first seem. Because words change their pronunciation over time and between dialects, so do rhyming patterns. In this way, a rhyming dictionary for Old English, or for Elizabethan poetry, would have quite different ryhming patterns.
If you have trouble compiling or using the rhymingdictionary on your system, please email me with the problem and a little bit about your system so I can help you fix it.
A slightly debugged version of that dictionary is included as pre-parsed gdbm files that any gdbm-aware language can search with a minimal of effort.
Because all the other rhymingdictionaries I've seen were either in dead tree format (which takes awhile to flip through), or were web-only (which would force me to be online constantly to use them) and I didn't like either approach.