1) Log into an irb session, and enter your S3 login details.

require 'rubygems'
require 'aws/s3'

  AWS::S3::Base.establish_connection!(
    :access_key_id     => 'REPLACE_ME',
    :secret_access_key => 'REPLACE_ME'
  )

output:
=> #<AWS::S3::Connection:0xb75e0594 @http=#<Net::HTTP s3.amazonaws.com:80 open=false>, @secret_access_key="", @options={:server=>"s3.amazonaws.com", :access_key_id=>"", :port=>80, :secret_access_key=>"", :persistent=>true}, @access_key_id="19S45GYAGWK8DC2B8VG2">

2) Browse the existing buckets.

AWS::S3::Service.buckets

output:
=> [#<AWS::S3::Bucket:0xb75cc850 @object_cache=[], @attributes={"name"=>"ogg.twitteraudio.com", "creation_date"=>Sat Apr 26 10:40:16 UTC 2008}>, #<AWS::S3::Bucket:0xb75cc83c @object_cache=[], @attributes={"name"=>"t1000", "creation_date"=>Fri Apr 25 21:35:21 UTC 2008}>, #<AWS::S3::Bucket:0xb75cc814 @object_cache=[], @attributes={"name"=>"t2000", "creation_date"=>Fri Apr 25 21:53:15 UTC 2008}>]

3) Browse the buckets in a programmatical way.

AWS::S3::Service.buckets.each {|b| puts b.name}

output:
ogg.twitteraudio.com
t1000
t2000


4) Add a new bucket called t3000.

AWS::S3::Bucket.create('t3000')

output:
=> true

5) Observe adding the bucket again doesn't cause an error.

AWS::S3::Bucket.create('t3000')

output:
=> true

6) View the buckets again.

AWS::S3::Service.buckets

output:
=> [#<AWS::S3::Bucket:0xb75cc850 @object_cache=[], @attributes={"name"=>"ogg.twitteraudio.com", "creation_date"=>Sat Apr 26 10:40:16 UTC 2008}>, #<AWS::S3::Bucket:0xb75cc83c @object_cache=[], @attributes={"name"=>"t1000", "creation_date"=>Fri Apr 25 21:35:21 UTC 2008}>, #<AWS::S3::Bucket:0xb75cc814 @object_cache=[], @attributes={"name"=>"t2000", "creation_date"=>Fri Apr 25 21:53:15 UTC 2008}>]

Note: You would expect t3000 to be in there however it didn't appear possibly because of the bucket permissions.

7) Let's then look for bucket t3000.

t3000 = AWS::S3::Bucket.find('t3000')

output:
=> #<AWS::S3::Bucket:0xb76df724 @object_cache=[], @attributes={"prefix"=>nil, "name"=>"t3000", "marker"=>nil, "max_keys"=>1000, "is_truncated"=>false, "xmlns"=>"http://s3.amazonaws.com/doc/2006-03-01/"}>

8) Now that we've found the bucket let's upload a text file called works.txt.

file = "works.txt"

output:
=> "works.txt"

AWS::S3::S3Object.store(file, open(file), 't3000', :access => :public_read)

output:
=> #<AWS::S3::S3Object::Response:0x-608926458 200 OK>

9) Setting the file access to :public_read allows us to view the file from the http location http://t3000.s3.amazonaws.com/works.txt

References:
http://amazon.rubyforge.org/
upload_to_s3 - Ruby S3 upload client [dzone.com]

*update: 14:30 30 April 2008 *
I didn't use Bucket.objects(:reload) which is the reason why the bucket t3000 didn't show up with the statement Service.buckets

Reference: spatten design - Amazon S3, Ruby and Rails slides [spattendesign.com]

Some simple S3 utils in Ruby

Specifically written to copy one bucket to another (for testing on production on staging)

PLEASE BE CAREFUL WITH THIS - THERE IS CODE THAT DELETES ALL CONTENTS OF A BUCKET

Example:

a = AmazoneS3Asset.new
a.copy_over_bucket("myapp_production", "myapp_production")

require 'aws/s3'
require 'mechanize'

class AmazonS3Asset
  
  include AWS::S3
  S3ID = "your s3 id"
  S3KEY = "your s3 key"
  
  def initialize
    puts "connecting..."
    AWS::S3::Base.establish_connection!(
      :access_key_id     => S3ID,
      :secret_access_key => S3KEY
    )
  end

  def delete_key(bucket, key)
    if exists?(bucket, key) 
      S3Object.delete key, bucket
    end
  end
  
  def empty_bucket(bucket)
    bucket_keys(bucket).each do |k|
      puts "deleting #{k}"
      delete_key(bucket,k)
    end
  end
  
  def bucket_keys(bucket)
    b = Bucket.find(bucket)
    b.objects.collect {|o| o.key}
  end

  def copy_over_bucket(from_bucket, to_bucket)
    puts "Replacing #{to_bucket} with contents of #{from_bucket}"
    #delete to_bucket
    empty_bucket(to_bucket)
    bucket_keys(from_bucket).each do |k|
      copy_between_buckets(from_bucket, to_bucket, k)
    end
  end
  
  def copy_between_buckets(from_bucket, to_bucket, from_key, to_key = nil)
    if exists?(from_bucket, from_key)
      to_key = from_key if to_key.nil?
      puts "Copying #{from_bucket}.#{from_key} to #{to_bucket}.#{to_key}"
      url = "http://s3.amazonaws.com/#{from_bucket}/#{from_key}"
      filename = download(url)
      store_file(to_bucket,to_key,filename)
      File.delete(filename)
      return "http://s3.amazonaws.com/#{to_bucket}/#{to_key}"
    else
      puts "#{from_bucket}.#{from_key} didn't exist"
      return nil
    end
  end

  def store_file(bucket, key, filename)
     puts "Storing #{filename} in #{bucket}.#{key}"
     S3Object.store(
      key,
      File.open(filename),
      bucket,
      :access => :public_read
      )
  end

  def download(url, save_as = nil)
    if save_as.nil?
      Dir.mkdir("amazon_s3_temp") if !File.exists?("amazon_s3_temp")
      save_as = File.join("amazon_s3_temp",File.basename(url))
    end
    begin
      puts "Saving #{url} to #{save_as}"
      agent = WWW::Mechanize.new {|a| a.log = Logger.new(STDERR) }
      img = agent.get(url)
      img.save_as(save_as)
      return save_as
    rescue
      raise "Failed on " + url + "  " + save_as
    end
  end

  def exists?(bucket,key)
    begin
      res = S3Object.find key, bucket
    rescue 
      res = nil
    end
    return !res.nil?
  end
      
end