Aviary is a suite of powerful creative applications that you can use right in your web browser.
"Aviary is a collection of ornithologically named online tools designed to bring creativity to the cloud. There is a strong focus on graphic work in the form of photo, vector and palette editors, but an online audio editor is also available." Tech Radar Review
100% freeAviary contains a number of terrific web-based photo editing tools.
Peacock is an impressive effects editor – also referred to as the Visual Laboratory.
Myna is the suite's multi-track audio editor. You're provided with a large number of samples that can be dropped into a track, but it is also possible to upload your own audio files.
The Aviary editor is embeddable. Make sure you allow yourself plenty of time as the only real downside being the extra time it takes to save large files.