Install applications onto Android emulator

First, find an application on Android Market.
http://www.android.com/market/

Using the Android SDK, open the emulator, then type following commands:

$sudo ./adb kill-server
$sudo ./adb devices
List of devices attached
emulator-5554 device
./adb install XXX.apk

After that, you will find it in application tap.

[Note] Some other command
1. adb shell (or adb shell + cmd)
2. adb push test.txt /sdcard
3. adb pull /sdcard/test.txt .
4. adb logcat

[Note2] http://developer.android.com/guide/developing/tools/adb.html