YPmobile - yellow pages.
iTalk - voice recorder. You can get iTalk sync to put them on your computer.
Easy Writer - easier to type an email since it lets you do it in landscape format.
AroundMe - finds all sorts of buisness based on gps. Banks, bars, coffee, gas, hospitals, hotels, theatres parking, phamacies, resturants, supermarkets, etc. (A PAing lifesaver)
Air Sharing - data transfer. store files on phone.
Folders - to save different docs
Spreadsheets
Air Mouse Pro - turns your phone into a computer mouse.