The Internet Archive is a non-profit organisation offering everyone - from dedicated scholars to the general public - free access to historical collections that exist in digital format. The Archive now includes text, audio and moving image-based materials as well as software and archived web pages. They also provide various adaptive technologies to allow greater access for the blind and people with other disabilities. www.archive.org
Flickr is an online photo management application that allows you to store and share photographs online. It provides you with the facility to upload your work under a range of Creative Commons licenses, providing useful information on all the different types of licences available and even allows you to search through content categorised by license.
The Freesound Project supports an open and collaboratively created database of sounds, all released under the Creative Commons Sampling Plus License. You can up and download sounds and interact with other sound-artists via the site, which is strongly encouraged - along with archives from various institutions - to help expand the database for future users.
Open Source Cinema
Open Source Cinema lets you create videos online by remixing media stored on your own computer as well as adapting the types of works you might find on sites like YouTube and Flickr. You can connect with the broader site community by sending personal messages, commenting on remixes, or even joining each other's projects. http://opensourcecinema.org/
The Prelinger Archives hold approximately 2,000 public domain films, available to download for free. They collect, preserve, and facilitate access to films of historic significance that can't be accessed elsewhere and actively encourage you to further share the films which can be reused and reproduced (in whole or in part) anywhere in the world. Derivative works become the property of the producer and can be performed, published, reproduced, sold, or distributed in any way without limitation. www.archive.org/details/prelinger
VisitorsStudio is a real-time, multi-user, online space for remix and play, dialogue and open networked performance. Through a simple and accessible interface, you can upload, manipulate and collage your own audio-visual files, work with other people's material and connect with users from around the world. Created by Furtherfield in 2004, it provides a realm where emergent and established artists from an array of geographical locations and social contexts can explore collective creativity together. www.visitorsstudio.org
Wikimedia Commons is a database of almost 10,000,000 freely usable media files to which anyone can contribute. Here, however, you are also allowed to modify media files (as long as you follow the terms specified by the author). Content ranges from that provided by large public institutional collections to individual artists - and the onus is on you to contribute your work, time and skills to improve the site. http://commons.wikimedia.org/wiki/Main_Page