One quick trick is to use a QR Code to get the key onto the phone.
Step 1) Turn the text into a QR Code. You can do this manually at http://qrcode.kaywa.com/ or try this bookmarklet. Just drag the link to your bookmark bar, highlight some text on a page and click on the bookmarklet.
Step 2) Scan the text into your phone. For the iPhone I used the free app "QR App". For Android I used the free app "Barcode Scanner".
Step 3) Copy the text. For iPhone with QR App just double tap the text and choose copy. For Android with Barcode Reader the text is automatically copied for you.
Step 4) Paste.
This is great for most things but if you really want to protect your password then sending it in a url in cleartext may not be the best way. For that, try this Javascript QR Code generator. Take a look at the source to convince yourself that it is all client side.
Javascript QR Code generator by Kazuhiko Arase.
