Deploy one of the free ubuntu images ( or any flavor linux you like)
Unpack torquebox2.2 to /opt
Unpack JDK1.7 under /opt/torquebox-2.2.0
Save the following to your bashrc
export TORQUEBOX_HOME=/opt/torquebox-2.2.0
export JAVA_HOME=/opt/torquebox-2.2.0/jdk1.7.0_10
export JBOSS_HOME=$TORQUEBOX_HOME/jboss
export JRUBY_HOME=$TORQUEBOX_HOME/jruby
export PATH=$JRUBY_HOME/bin:$JAVA_HOME/bin:$PATH
And you are done. Unless you mean an image that has examples of sites deployed using torquebox.