Spendabit is a search engine for things you can buy with Bitcoin. It searches across and aggregates products from thousands of merchants across hundreds of data sources (eCommerce websites, CSV data feeds, etc).

Spendabit is a Scala-based application leveraging PostgreSQL on the back-end for general data storage and for search (using the PostgreSQL Full Text Search extensions), as well as a number of Java and Scala libraries (such as Slick for database access). It leverages state-of-the-art "scraping" (web crawling) technology to import, and keep up-to-date, the majority of its products.

DownsizeDC.org is an educational venue, but also a platform for (primarily US-based) people to advocate the case for liberty on a multitude of issues. The most notable component is the "Educate the Powerful" system, which presents a very simple user-interface atop a powerful back-end that automates the web-based contact forms of members of the US Congress, using a large set of rules and heuristics. It handles several hundred contact forms without the need for website-specific rules or coding, and even handles Captchas and other similar roadblocks.

Its functionality is probably best illustrated by visiting and interacting with one of the campaigns. Here is the URL for the "Read the Bills Act" campaign, for example: https://downsizedc.org/etp/rtba/

DowsizeDC.org is a primarily PHP-based application with PostgreSQL as the data store.

The polling and petitioning application at ZeroAggressionProject.org aims to both recruit people to the position of the Zero Aggression Principle (a.k.a. Non-Aggression Principle) and offer a platform for recruitment and advocacy to existing adherents to the principle.

The application presents potential respondents with a series of "panels" positing facts, questions, hypothetical scenarios, and general arguments regarding the particular "campaign" (for example, "drug prohibition" or "immigration"). Responses are recorded in a database and re-presented to users in a visual fashion.

The back-end is written in Scala, leveraging the Scalatra micro-framework, with PostgreSQL as the data store. The front-end makes use of Bootstrap and jQuery.

BitcoinChipin.com is a bit of a pet project but presents a clean, elegant user interface. It is a simple tool that provides users with a graphical widget, embeddable on their own website or blog, which they can use to encourage people to donate, via Bitcoin, to a particular cause (e.g., "Help us feed the homeless").

BitcoinChipin.com is mostly PHP-based, with MySQL for the database, and Bootstrap and jQuery for UI components. It uses the Blockchain.info API for interacting with the Bitcoin network (retrieving balances).