If you have a model (User, Account, etc..) and you only want invited people to be allowed creating those resource. Good example is while in beta, invite only account creation.

A Light weight invitation system for Ruby on Rails.

Rails Engine for single-entry invoicing.

invoice is created.

This is a framework for generating and displaying invoices (ideal for commercial Rails apps). It allows for flexible business logic; provides tools for tax handling, commission calculation etc. It aims to be both developer-friendly and accountant-friendly.

An XML-RPC Client for the API of INWX.

API access to Inxmail

A Ruby SDK for integrating with the Complyance Unified e-invoicing platform, supporting multiple countries and document types

Samuel Williams' engines plugin.

Easily create customizable CRUD based controllers with Information Oriented Representation of Data

Nicely documented Push Notification gem for rails 3 applications, has generators for migrations and an initializer with configuration. It is well documented and tested.... compared to other shitty forks out there >_>

Creates a Rails 3 app

Block your unwanted visitors.

iPhone specific HTML tags helper

This gem allows ActiveRecord models to generate, validate, and clear OTP codes with an expiration time.

Provides /worker-heartbeat endpoint handling, persistence, delayed callback job, and failure-only email alerts.

IpToCountry is a simple rails tool to determine the origin (ISO country code or country name) of an IP address. The gem uses data from GeoLite by MaxMind.

Read the IP Address of a visitor to your website and tweet it.

MVC based Math, Logic Captcha

A Rails kernel for Jupyter frontends (e.g. notebook). Try it at try.jupyter.org.