How to have trust in a Community AMI offered on Amazon EC2

I understand you are using Ubuntu on EC2 and you have logged in successfully using SSH keypair authentication.

You don't need the root password to use sudo, that's the point of sudo.

Set the password for your current logged in user using the command, "passwd".

If your user is already in the sudoers file, then you should now be able to sudo using the password you have just set.

Link provided Istvan is down.

Amazon now provides tool to export your EC2 image as Virtual Machine image ready to run locally:

http://aws.amazon.com/ec2/vmimport/

PS Please note that this method only works for Windows VMs

Export the instance using the ec2-create-instance-export-task command. The export command captures the parameters necessary (instance ID, S3 bucket to hold the exported image, name of the exported image, VMDK, OVA or VHD format) to properly export the instance to your chosen format. The exported file is saved in an S3 bucket that you previously created

October 2016 update: You're able to create VM images from several Unix/Linux AMIs as well