Here's a nifty word app that downloads a new word to learn every day. One good thing about it is that it actually has audio samples too so you can listen to them so that you know how to say it.
http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=307683577&mt=8
http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=307683577&mt=8