I've been searching around to see what kinds of language learning applications are available for different phones. Byki have developed an app for the iphone which helps learners study a variety of languages and English of course is one of them, though specifically designed for speakers of Chinese, Japanese, Korean, Portuguese and Spanish who are learning English).
I haven't had a chance to try out the app as I don't have an iphone, but there are a couple of interesting things to note about it. First, some of the content is user generated, they have vocabulary lists/lessons added to their server from users for others to download. Nice idea.
Secondly, the the design of the software is informed by certain views on language learning that could be broadly described as lexical. That is, we learn languages by 'chunking' common fixed phrases together and our focus is much more on vocabulary rather than on learning the abstract rules of grammar. Whether that's true or not is highly debatable, but it is interesting to read the theoretical underpinnings of the software and to see something that is not purely phrasebook software. You can read more about their theoretical background here.
They do have a desktop version of the their software as well. I downloaded the trial version but couldn't get it to work on my computer. So, doesn't seem I'm in any position to evaluate whether the Byki software is any damn good or not, but I am intrigued by it and would be interested to hear if anyone has tried it out and what they thought of it. This video takes you through some of the features and I like the slow down option for pronunciation, but would like to hear real user stories with this.