i2Speak is an online Smart IPA Keyboard that lets you quickly type IPA phonetics without the need to memorize any symbol code. For every Roman character you type, a popup menu displays a group of phonetic symbols that share the same sound or shape beneath typed character.
You can test the tool here: http://www.i2speak.com
i2Speak is a product by sciweavers.org, an academic network for scientists and researchers.
Chinese teachers will also be interested in online tools for BoPoMoFo, Pinyin, Cantonese, and Cangjie input methods.
There is also an input tool for Arabic script.