Copy ssh keys for password-less access

I created an EC2 HADOOP cluster via Whirr.  Now I want to give my co-workers access to it.
Here is my solution.  First generate new keys then upload the public key to the server.

# Symbols $=local, $$=server

# Generate new keys on her workstation
$ ssh-keygen -t rsa -P ''
cindy@ubuntu:~/.ssh$ ls
id_rsa_ec2
id_rsa_ec2.pub

# Copy id_rsa_ec2.pub to the server
You can use scp or secure transfer to amazon s3

# Since I already have access to the server, I'll just ssh to the server and add cindy's pub key
$$ chmod 600 ~/.ssh/authorized_keys
$$ cat id_rsa_ec2.pub >> authorized_keys
$$ chmod 400 ~/.ssh/authorized_keys

# Back to her workstation
$ ssh ec2-user@ec2-10-11-12-123.us-east-1.compute.amazonaws.com


Done!

If you think there's a better way.  Please let me know.  Thanks