Previously we have discussed various external keyboard options for use with the iPad. These Bluetooth keyboards were integrated into a case and while larger than the iPad virtual keyboard, were still smaller than standard size. We have located an iPad compatible USB full size rubber keyboard that rolls or folds into a very compact size. The keyboard is marketed under the iConcepts brand (iConcepts-M01917-MB Foldable Keyboard) sells for only $14.99 at Bed Bath & Beyond, of all places (and can be found on the Web for less than $10).
We have tested the keyboard on iPad and iPad 2 and the keyboard works well with both, although there is an unsupported device notice when the USB connector is placed in the iPad.
On a related note, I have had an iPad 2 for only a day now. While I appreciate the lighter and thinner profile, the new iPad seems much more fragile. I have found that the rubber keyboard folded in half will easily fit in my Swiss Army carry case with the iPad 2 w/ smart cover, providing additional shock absorber support in the event of a drop.