Rhyming

Alcor Rhyming Dictionaries
Online rhyming dictionaries in Spanish, French, Italian, Portuguese, Romanian, and German.
http://www.alcor.com.au/rhyming_dictionary.asp

AnalogX - Rhyme
[Windows] A rhyming program. Knows over 100,000 words. It can rhyme words forward, backwards, and with matching syllable counts.
http://www.analogx.com/contents/download/audio/rhyme.htm

Lexical FreeNet
Allows you to search for rhymes and relationships between words and concepts.
http://www.lexfn.com/

Semantic Rhyming Dictionary
Rhyming dictionary and thesaurus: rhymes, near rhymes, homophones synonyms, and semantic siblings of English words.
http://www.rhymezone.com/

Word Central
Student dictionary and rhyming dictionary online at Merriam-Webster's website. Daily Buzzword by subscription.
http://www.wordcentral.com/

WriteExpress Online Rhyming Dictionary
Online dictionary for poetry and songwriting.
http://www.writeexpress.com/online.html