I'll go ahead and assume you mean ec2 only by the tags on your question.
If you are using an EBS root image, this is as easy as
ec2-create-snapshot. You'll get a block device which you can attach to another machine and copy anywhere. Its important to note that these are in the same availability zone as the instance, so don't rely on the snapshot alone for surviving an availability zone going down.
If you are on an ephemeral drive (sometimes called the "instance storage"), you will need to do it the old fashioned way, by copying all the data off your instance. One lightning fast way to do this is to use something like s3cmd to sync all your data into an S3 bucket. You can get the s3cmd tool in the