Some terrific web based applications for image editing and online storage allow users to enhance and share media files without the need to purchase or download space consuming software. Services and specialties vary between sites I'm visiting which include:

• Media: Image Editing & Sharing
• Photoshop.com
• FotoFlexer 
• Lunapic
• Picnik
• Picasa
• Pixlr
• PicApp 
• Phoenix
• Media: Image Hosting, Sharing & Albums Online:
• Image Shack
• PictureTrail
• Flickr
• Photobucket
• Slide.com
• Slideroll.com [flash]

Two image editors with free version downloads and features similar to more expensive software on the market are:

• Paint.net
• Gimp