FnordMetric is an open source web application for creating real-time dashboards that can visualize the data you want.
It uses Redis as the datastore (if you have the date in another db, it should be pushed there) and allows defining our own plotting + counting functions as Ruby blocks.
The application has a UI for for visualizing the data and, also, it offers an HTML5/JavaScript API for inserting charts/data into web pages as widgets.
FonrdMetric has a detailed documentation from its installation steps to API usage.
Requirements: Ruby on Rails
Balloons.IO is a very impressive and open source chat application that is built with node.js, Express, Socket.IO and Redis.
It has support for multiple rooms where users can join any of them, chat with other users and send files to each other.
Also, there is an option for users to create their own rooms and set their statuses (available, away, busy)
The application is simple-yet-solid and requires users to login with their Twitter accounts (which is good to keep the quality "up" but can be limiting). It also automatically fetches the avatar and uses is with every message of each user.
Requirements: node.js & Redis
Compatibility: All Major Browsers
