Quoting the README at http://github.com/vjoel/crown/tree/master :

The *crown* program gathers gem lib and bin files under one directory 
for fast loading and predictable behavior. For example:

   [~/tmp] crown -v mygems json nokogiri sinatra
   sinatra-0.9.4
   nokogiri-1.3.3
   json-1.1.7
   rack-1.0.0
   PATH=/home/vjoel/tmp/mygems/bin
 
RUBYLIB=/home/vjoel/tmp/mygems/ext:/home/vjoel/tmp/mygems/ext/json/ext:/home/vjoel/tmp/mygems/lib

The gems are copied under mygems:

   [~/tmp] ls mygems
   bin  ext  lib
   [~/tmp] ls mygems/lib
   action-nokogiri.rb  json.rb   nokogiri.rb  rack.rb  sinatra.rb
   json                nokogiri  rack         sinatra  xsd

The output of 'crown -v' shows you which gems (and versions) it is 
gathering, including all dependencies, and it shows you the PATH and 
RUBYLIB you need to use those files:

   [~/tmp] export RUBYOPT=''
   [~/tmp] export 
RUBYLIB=/home/vjoel/tmp/mygems/ext:/home/vjoel/tmp/mygems/ext/json/ext:/home/vjoel/tmp/mygems/lib
   [~/tmp] ruby -r json -e 'p JSON'
   JSON

Why?

* You can stop requiring 'rubygems' and you don't need 
RUBYOPT='rubygems'. There are no runtime dependencies on rubygems.

* Lookups for required files should be faster.

* No chance that "gem update" or "gem cleanup" might break your program.

* You can distribute the "crown of gems" with your program.

Features:

* Either symlink files (-s switch) or copy files (the default).

* Include other non-gem files using dest:file syntax.

* Existing files in the target dir are not touched if they are not in 
the way.

* Works correctly even with gems that have strange require_path lists, 
like json.

* No dirs are ever deleted or replaced.

* A file is written only if either it doesn't already exist in the 
target dir or you specify the force (-f) switch.

* The verify (-V) mode checks whether the target dir looks like it has 
had the crown command run on it with the given arguments.

* Dry-run (-n) and verbose (-v, -vv) options, as in FileUtils

See the help (-h) for details, license, version, and contact information.

This software is not fully tested on all gems; please test carefully 
before using in production environments.

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407