I wrote about the revolutionary e-dictionary Wordflex last week. During the past week I have become very convinced that is is one of the iPad apps every English-speaker needs. Especially every student.
I have explored a bunch of words and semantic networks and it has been a huge help to me. And, since it is backed by the Oxford Dictionary family, there is brilliant content within the database. This is a product where you don’t balk at the price; if you get it you will use it.