Sorry, but you can't. The only photo transferring that can be done is TO the iPad and that's with using the camera connection kit (CCK) to get photos from a camera.
To get photos from the iPad, you'll need to use iTunes, an online storage account such as Dropbox or via e~mail. There is no way, at present, with a stock iPad, to use a USB stick or SD card.
Sorry.
Marilyn