ElastDream is an open source GUI system admin tool for Amazon EC2, RDS and Eucalyptus. It is an experimental tool to look at ways of automating cloud computing system administration tasks. It is written in Ruby using FXRuby for a cross-platform GUI. It is easy to modify the code or change features. Support for Amazon EC2, and Eucalyptus:

Multiple environments based on access key, region and keypair.  A tree view of your servers.  One click SSH, SCP and Remote Desktop access.  Script for one click bundling of an instance.  One click deregister and delete Image.  Launch and terminate EC2 and Eucalyptus Servers  View Server's System log  Save Launch profile  Ability to build and run remote scripts.  Server scripts to provide auto mount of EBS, and synchronisation of dynamic IP address.  Support for Ruby for Linux Servers.  Support for Powershell for Windows 2003 Servers  Create, Delete, Display, Authorize, Revoke Security Groups  Create, Delete, Display, Attach, Detach EBS Volumes  Create, Delete, Display EBS Snapshots  Create, Delete, Display, Associate, Disassociate Elastic IPs  Create, Delete Keypairs  Register, DeRegister Images.  Monitoring Graphs  Scripts for applications  Nicknames for EBS and snapshots Support for Amazon RDS:  Launch and terminate RDS Servers   Create, Delete, Display DB Snapshots  Create, Delete, Modify DB Parameters  Modify DB Instance  View DB Events  Restore DB from Snapshot and to point in time   Once click access to MySQL Administrator GUI         It contains: Ruby for scripting. 
Capistrano for remote scripting. 
For Linux servers there are server scripts in ruby. 
For windows servers there are server scripts in powershell. 
PuTTY for Windows SSH access. 
winSCP for Windows remote file copying.  
launchRDP for launching Windows remote desktop.

For more info on using ElastDream with Amazon EC2 see the Getting Started Guide

For more info on using ElastDream with Eucalyptus see the Getting Started Guide with Eucalyptus

For more info on using ElastDream with Amazon RDS see the Getting Started Guide with Amazon RDS

It is simple to install and replaces multiple tools currently required to administer Amazon EC2.

It is the only Graphical System Admin for Eucalyptus that you can install on your client.