Ive been loading blockchain.info wallets and making QR codes of the Keys and putting the passwords underneath.
Hopefully there are instructions given to the recipient to change the password before adding any additional funds to the wallet.
For convenience the private key from a note handed out can be imported into a Blockchain.info/wallet and a card with that wallet's URL be handed out as well. Thus the recipient has a piece of paper that can be exchanged with someone else, but also has that amount online, needing nothing more than to log in before it can be spent.
A few times that I've handed out paper bitcoins at functions I've hand-printed an expiration date (e.g,. 30 days from the event date) as only a fraction of them actually ever get redeemed by the recipient. But putting on the expiration date I am able to avoid wasting any funds to recipients that didn't choose to participate. This lets me distribute a higher amount (e..g,. 0.1 BTC) in situations where this is out of pocket. There might be only 1 out of 10 who actually redeems the funds, unfortunately (depending on your audience). So simply after the expiration date the funds are reclaimed and reloaded onto additional paper bitcoins to be used at some future event.
