Sharing apps with friends is great, but can be annoying when they have to search for apps you recommend to them. With free app App Referrer, you can generate a quick QR code and send them to the Market instantly.
We've all been in that situation: you're sitting next to your friend, with both your phones out, and you tell them about this "awesome new app you found". Then he or she has to pull up the Market and manually search for the app ("What's it called?" "Space or no space?" "It's spelled with leet speak?"). There are a number of ways to share files and apps between phones, but App Referrer keeps it simple — you don't need to set up any kind of connection between the phones, just open it up, tap the app you want to send, and it'll generate a Market QR code that they can scan right then and there. Pretty handy if you happen to be in a gang full of Android users. If you prefer, you can also send Market links via SMS, email or Twitter if you're not right next to the friend in question.
App Referrer is a free download for Android phones. Incidentally, the QR code in the above screenshot will take you to App Referrer's entry in the Market.