You can read more about the app here.
I don't have an iPhone or iPod touch, so I haven't tried this. BUT, I have five codes for a free download. Note - before I said it was a 30-day trial, but it's actually the code itself that expires in 30 days; the download is free to use as long as you'd like! If you're interested, e-mail me at waronheadaches at gmail dot com and I'll send you details!(Image by BetterQOL)