Photo/Video Galleries and Photocasts
Online photo galleries were another one of the services included when Apple launched iTools, and this eventually evolved into the current MobileMe Galleries that can host photo albums and video for access in a stunning web interface and which can be accessed as slideshows on iOS devices including the Apple TV.
Along the way, Apple link MobileMe Galleries to both iOS and Mac OS X in other ways. MobileMe gallery sharing has been a staple in the Camera and Photos apps in iOS. Similarly, iPhoto allows Mac users to easily publish photos to MobileMe Galleries. Apple also created an iPhoto feature known as Photocasts that published an RSS feed for albums published to MobileMea feed that other iPhoto users can subscribe to in order to have new published photos synced to their iPhoto library (non-iPhoto users could also subscribe with any standard RSS reader for Mac OS X, Windows, iOS, or other platforms).
It goes without saying that there are endless ways to easily share photos online today, be it from your iPhoto library, your iPhone/iPad, or almost any other application or device. Some of the simplest include general social networking sites like Facebook, Twitter (with its new built-in sharing service) or one of the many third-party options like TwitPic, yfrog, and img.ly, and Google+ along with photo-specific sites like Flickr, Picasa, Photobucket, Photoshop.com, and Shutterfly, or even blog services like Blogger, Wordpress, and Tumblr.
Sharing video is just as easy, and while YouTube is generally an obvious choice, other options include Blip.tv, Vimeo, Veoh, Yfrog, and TwitVid (generally used with Twitter, though TwitVid also supports login using Facebook), and the video-sharing features built into Facebook, Google+, and even Flickr.
With such a wide range of options, choosing the best one(s) for your needs can seem daunting. One way is to use services natively supported by the software or devices you use. iPhoto, for example, offers one-click sharing to Facebook and Flickr as well as the ability to view/subscribe to published albums such that they're displayed in your iPhoto library much like MobileMe. Flickr can also be browsed from an Apple TV just like MobileMe Galleries. Similarly, Apple's iOS 5 will offer integration with Twitter's new built-in photo service for native sharing direct from the Camera and Photos apps like MobileMe has up until now.
Another option is to consider how you're used to sharing content online. If you already keep a personal blog, that may be a better choice. If you use one or more social networks as a primary way to keep in touch with people, they may be better suited.
Finally, you may want to consider how you want to make use of online photos beyond quick sharing. Dedicated photo sites like Flickr, Picasa, Photobucket, Shutterfly, and Photoshop Express offer you ways to connect with other photographers, organize and edit photos, and even order prints of photo merchandise like cards or books (though some of these features are available in iPhoto and other Mac/Windows/iOS photo apps).