iPhoto overhead and the iPad
The easiest way is probably the camera connection kit: http://store.apple.com/us/product/MC531ZM/A?fnode=MTc0MjU4NjE

But, depends on the app. I've found drop-box to be very easy for simple file transfers.

If you open iTunes you can also configure which files can be copied into which app under the App tab when you control the device.