Paste this exactly to get your MD5 key:
C:Program FilesJavajdk1.6.0_20bin>keytool.exe -list -alias androiddebugkey –
keystore “C:Documents and Settingstest.androiddebug.keystore” -storepass android -keypass android
Also there is a bug in eclipse, where in you will get a greyed out map with only tiles. Use this to correct that:
The solution was to set the “Custom debug keystore” setting (empty by default) to the same value as the “Default debug keystore” in the Eclipse preferences.
Second Option:
1) Open up your project in eclipse.
2) Right click your project and click on option as shown in the picture below:

3) Follow the instructions as shown below to generate a keystore:

4) Use a MD5 tool to retrieve the MD5 signature.
5) Goto http://code.google.com/android/maps-api-signup.html to get your google maps api key.
Note: this signing works only for debug version of the app.