The following are links to sites outside of this project that may be useful in gaining more background knowledge, further study, and other resources regarding tongue twisters.
The Links:
A giant online resource of tongue twisters in 119 languages, "1st International Collection of Tongue Twisters": http://www.uebersetzung.at/twister/index.htm
Yet another large online inventory of tongue twisters, only featuring English by alphabetized by the most frequent letters in the tongue twister: http://thinks.com/words/tonguetwisters.htm
An article from the University of Cambridge's Matt Davis who did some research on a 2003 spam email claiming the letter order in words doesn't matter to English speakers: http://www.mrc-cbu.cam.ac.uk/people/matt.davis/cmabridge/index.html
Another article from Matt Davis detailing Graham Rawlinson's PhD Thesis from 1976 on the significance of letter position in word recognition: http://www.mrc-cbu.cam.ac.uk/people/matt.davis/cmabridge/rawlinson.html
A website with recordings of British English speakers that is particularly useful in classroom settings for younger children: http://learnenglishkids.britishcouncil.org/en/tongue-twisters
Another teaching website sponsored by the British government to promote the use of tongue twisters to, "help students develop their pronunciation,":http://www.teachingenglish.org.uk/try/resources/audio-bank/tongue-twisters
Other resources:
Inventory of IPA symbols featured in this site in raw XML: 13 KB
Corpus of English tongue twisters in raw XML: 4 KB
Schematron document used to verify the IPA Inventory: 1 KB