Flexible open-source content management and blogging software with an active user and developer community and a wide variety of plug-ins or extensions available.
Full-featured open source office productivity suite, featuring word processor, spreadsheet, presentation, drawing and database packages; free MS Office replacement.
Social networking for non-social purposes with a focus on professional development, networking for jobs and problem solving through the expertise of those in your extended network.
Convio is a modular hosted solutions that provides functionality for specific online activity (fundraising, advocacy, events), with email and Web publishing tools.