Bad news. The server hosting The Ruby Toolbox went bust on the evening of June 7th. While I do have backups, the original source code is in a very outdated state so I currently don't feel it makes sense to try and get it running again.

For the time being, here is a very stripped down version of the Ruby Toolbox's contents.

Update June 13th: I'd like to invite you to join the discussion on the future of the Toolbox on github. You can also get in touch directly on Twitter.

Christoph
 Score 8.45

chunky_png

This pure Ruby library can read and write PNG images without depending on an external image library, like RMagick. It tries to be memory efficient and reasonably fast. It supports reading and writing all PNG variants that are defined in the specification, with one limitation: only 8-bit color depth is supported. It supports all transparency, interlacing and filtering options the PNG specifications allows. It can also read and write textual metadata from PNG files. Low-level read/write access to PNG chunks is also possible. This library supports simple drawing on the image canvas and simple operations like alpha composition and cropping. Finally, it can import from and export to RMagick for interoperability. Also, have a look at OilyPNG at http://github.com/wvanbergen/oily_png. OilyPNG is a drop in mixin module that implements some of the ChunkyPNG algorithms in C, which provides a massive speed boost to encoding and decoding.

 Rubygem chunky_png
 Score 4.2

MiniMagick

Manipulate images with minimal use of memory via ImageMagick / GraphicsMagick

 Score 3.3

RMagick

RMagick is an interface between Ruby and ImageMagick.

 Rubygem rmagick
 Github rmagick/rmagick
 Score 0.27

Image science

ImageScience is a clean and happy Ruby library that generates thumbnails -- and kicks the living crap out of RMagick. Oh, and it doesn't leak memory like a sieve. :) For more information including build steps, see http://seattlerb.rubyforge.org/

 Score 0.24

image_sorcery

A ruby ImageMagick/GraphicsMagick library that doesn't suck

 Score 0.2

magickly

A service for image manipulation - built as an extensible wrapper of Imagemagick which handles caching, c/o the Dragonfly gem.

 Rubygem magickly
 Github afeld/magickly
 Score 0.19

skeptick

Thin ImageMagick DSL with smart command composition

 Rubygem skeptick
 Github maxim/skeptick
 Score 0.18

paperclip-optimizer

paperclip-optimizer is a Paperclip processor for optimizing and minifying uploaded images.

 Score 0.07

Devil

Ruby bindings for DevIL cross platform image loading library

 Rubygem devil
 Github banister/devil
 Score 0.04

Im magick

 Score 0.04

mojo_magick

Simple Ruby stateless module interface to imagemagick.

 Rubygem mojo_magick
 Score 0.02

core_image

Simple image manipulation using Apple's Core Image technology. Scale, rotate, flip, convert, overlay, and more.

 Rubygem core_image
 Score 0.01

image_squeeze

a library for automated lossless image optimization

 Score 0.0

MIAConverter

Turns a video file into an animated gif.