I dont have an iPhone or iPod Touch, but after reading a post "Seven Must-Have Offline Apps For Your iPhone/iPod Touch" at ReadWriteWeb, I might consider getting one to take advantage of the fabulous applications for offline reading, working with documents, and to take some work load off my current cell phone.
The first application Evernote will let you take notes ( voice and text) online and offline. Stanza is basically a reader that ports eBooks wirelessly off your PC and then you are free to read them with, or without Internet connection.
Working with Google documents ( word format ) and spreadsheets ( Excel format) is a breeze with MiGhtyDocsiPhone application and if you want to have an RSS reader get Byline( $2.99 application) with 2-way synchronization to Google Reader. Byline will also allow you to star (mark), "share, add notes, and email your RSS feeds, just like in Google Reader itself."
Anyone that follows the blogosphere knows how many interesting iPhone/iPod Touch applications came up recently on iTunes and I am glad that I can refer you to some basic ones too. If you want to check more applications, please go to the App Store in iTunes.