Conversation English is an iPhone/iTunes app where people can view a short video of a dialogue and do exercises. If your students are crazy about their smart phones, this would be a good way to get them to practice.
Mailvu is a free video messaging system that looks simple and easy to use. R. Stannard's video helps you get started quickly, and he also discusses how he uses the tools with his students for language learning: you can have students send you video recordings and then comment on them, have students do interviews of each other, describe something, talk about a holiday or their weekend, etc. Mailvu also has apps for Android and iPhone.
This might be a great tool for an extended project, e.g., have your students create an infospot audio guide to their local community. Lots of examples are linked on the front page, and there is an iPhone app to scan, listen, and record wherever you happen to be. There are currently over 1300 guides created by users, and more coming.
Audio and some video titl at these sites are free. I think you might be able to use a desktop recorder like Audacity to record a book to a set of files to take with you, or put on an iPhone. (Avoid the ads at the top of this page--the article is below.)
"We are a mobile & web platform that effortlessly allows you to record and upload audio for your friends, family or the rest of the world to hear." Can record from computer or iPhone/iPod. Great mobile recording for podcasting. Very easy to use. You can log in with your Twitter account, record or upload a file, send to friends and post to Facebook at the same time. Your file shows up with your profile next to it. Use is fully described by Russell Stannard at http://www.teachertrainingvideos.com/audioboo/index.html.
Audiobook is a mobile and web platform that lets you or your students create podcasts with computer or iPhone/Android. Stannard's video shows how to use it.