Picasa Web is a digital photo and video organizing website where you can backup photos and videos to share with others. It allows you to edit photos, make them look better with single-click easy features. You can organize the photos with albums, folders, tags, faces and places. It allows you to upload large photos for upto 1GB. The storage limit for larger photos (2048x2048 pixel) or smaller (800x800 pixel) is unlimited. If your limit is reached, then photos are automatically resized.
You can install PicBackMan's Picasa uploader for Mac from the website and start backing up photos and videos.