Did you get featured by apple? sounds like the kind of thing they would feature. Otherwise my best guess is to (a) offer an educational discount, and (b) try and get in contact with International Student Centres at various universities, since that might be a population which could use your app and is likely to have an i-device.
Also: isn't $4.99 a bit much for a reference app... I mean: they've got google.
anyway, just my two cents
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What's the best way to spread the word about our new app for the ESL market?
Svetlana2010 says,
We just released an educational app that teaches over 300 of today's most popular American English expressions and idioms through an interactive e-book. What is the best way for us to get the word out about this app -- including in markets outside the USA? Here's a link:
http://itunes.apple.com/us/app/english-at-work/id398332055?mt=8