Here are some useful sites for resources and reasearch:

Alexander Technique helps you develop a positive head-neck-back relationship which aids freedom of the voice.

The Roy Hart Theatre work to develop and explore the emotional expressive voice, working towards the full 8-octave vocal range.

Here you can find example recordings of many accents from around the world. An invaluable resource to actors and people interested in accent.

David Crystal’s blog is a fountain of linguistic thought often exploring the idea of a Global English.

Here you can find hundreds of articles on language and voice covering everything from internet language to Shakespeare…

This site is a great resource for pronunciation exercises, vocabulary, and many other tips of speaking English as a second language.

This site has a catalogue of videos of speakers around the world speaking texts in English. They focus on the mouth of the speaker so that you can see exactly what is going on in order to reproduce that accent.