Persist remote JSON APIs locally and vice versa

Gives you a fist full of code metrics

XMPP compatible reach chat organizer

Jeka is an awesome build/test/benchmarking tool

add Jenkins tasks to Capistrano

Ripped out the versioning rake tasks from jeweler

generate modern html scaffold

Painless verb conjugation

Jigsaw.com API. Incomplete coverage.

first jini gem

Jitsu is a frontend or meta build system for Ninja (http://github.com/martine/ninja), a lightning-fast but in itself (and by design) feature-poor build system. Jitsu reads project descriptions and generates Ninja buildfiles.

Simple rails generator that creates a view helper to add joliprint button to your view

a library that reads and write ledger format ledger files

Ruby interface to the joyent cloud API

No more need to download JQuery UI... just include jqueryui/yourtheme and everything just works! Rails 3.1 and up...

A simple standalone jetty launcher for jruby rack apps

Provides a gem library generator and helpful rake tasks

read more details on http://www.sencha.com/blog/2010/10/21/make-a-javascript-formatter-with-v8-and-jsbeautifier/

Little library that encapsulates a (particular) standardised way of talking between a service and javascript. Probably not the best way of doing things, but it's been handy in a pinch.

Javascript deferring to improve page speed. It moves the Javascript includes to the end of view, allowing the full rendering before start to download and execute scripts.