Cronofy - Unified Calendar API for developers
Charitable - A WordPress donation plugin that gives you full control over your fundraising experience.
Calendarix - Calendarix is a powerful and easy to use web-based calendar that runs on PHP and MySQL.
Give - A WordPress plugin for easily collecting donations
Campaign Calendar - Campaign Calendar by Bracket Labs builds a marketing calendar from your Salesforce Campaigns.
FreeFunder - Free crowdfunding platform with no platform fee and donates to your fundraiser based on shares!