The CMU Pronouncing Dictionary  
   A machine-readable pronunciation dictionary for North American English that contains over 100,000 words and their transcriptions.
   http://www.speech.cs.cmu.edu/cgi-bin/cmudict

Dictionary of English Phonesthemes Part 1  
   Relation of word sounds to meanings.
   http://www.geocities.com/SoHo/Studios/9783/phond1.html

Roger's Reference - A Complete Homonym and Homophone Dictionary  
   Dictionary of words that are phonetically identical but which have different meanings. Now includes over 5000 homonyms and homophones, with meanings and cross-references.
   http://rogersreference.com/

AsifSound vs. Spelling - American Dictionary  
   Spelling glossary indexed by its abstract grouping pronunciation (=Asifsound). AsifSound consists of 12 sound symbols. This is made from CMU Pronouncing Dictionary.
   http://www5d.biglobe.ne.jp/~the_imai/asifsound_dict.htm

American Homophones  
   List of American English words that sound the same (or very nearly the same) but are spelled differently.
   http://www.peak.org/~jeremy/dictionary/chapters/homophones.html