I've tried a few keyboards with my iPad, but never really relied on one as:
- Its something else to carry
- Unless you have a table to lean on, its nearly impossible to balance a keyboard and the iPad on your lap.
While the iPad in my mind is still very much a touch device, I recently picked up an InCase Origami case for my Apple wireless keyboard. The Origami is a case just for the small Apple Bluetooth keyboard, but it folds in a rather unique way that allows it to also function as a pretty useful stand for the iPad when opened. Even better, the iPad itself can remain in many cases and still be put in the Origami and be kept steady enough to sit in your lap without a table. If you are looking to use your iPad as a laptop replacement, the combination of the Origami case and the Apple Bluetooth keyboard is a good match.