Spotify: Released to much fanfare, Spotify is as close to a great streaming service we can get. The Android app lets you listen to all of Spotify's 13 million track library and with an offline mode, can even do it without a connection because you can wirelessly sync your local files to your phone, create and sync playlists and more.
Zaarly: It's sorta like Craigslist but it's prettier than Craigslist and made for your phone. The app connects buyers who post what they want to buy and sellers who post what they want to sell. Anything can be posted really, activities, services, stuff, etc. Obviously only works if people around you are using it. Free.
MyAppSharer: MyAppSharer lets you share apps to your friends by sending them a link to the Market or even the APK directly. Lifehacker says it's the most versatile way to share app recommendations and is especially great for apps that have been pulled from the Market already. Bluetooth, Email, Dropbox, SMS, or QR code, the other person doesn't even need MyAppSharer installed to receive them.