Dispite there being only a 32bit version of the android SDK, you can still work with it on your 64bit machine, make sure you have the following packages installed:

Debian, Ubuntu, etc

apt-get install ia32-libs
apt-get install sun-java6-jdk

Fedora, CentOS, etc

yum install glibc.i686 zlib.i686 libstdc++.i686  

Download the 32bit SDK

wget http://dl.google.com/android/android-sdk_r18-linux.tgz

(If link is dead see Reference)

Extract and change into the newly created directory and run tools/android update sdk –no-ui.
This will start updating everything in the SDK – Note this will take a while.

You should now be ready to start developing.

Reference
http://stackoverflow.com/questions/2710499/android-sdk-on-a-64-bit-linux-machine
http://developer.android.com/sdk/index.html