I have been looking at various photo sharing sites and must say that Smugmug does on heck of a job. Although it is not a free service Smugmug's design does deliver to end users luscious galleries that can be exported into flash players which can be embedded into blogs and other platforms. There are various levels of membership and an excellent customer service. Smugmug is a small family business which was started in 2002 on a "Shoe string" budget. In 2007 revenue hit the 12 million dollar mark and they are making a profit according to the LA TIMES.
In a nutshell - SmugMug allows the upload of an unlimited number of photos for all account types. - Includes a published API which allows programmers to create new functionality.
XML-based RSS and Atom feeds. - An email upload interface to allow camera phones to upload images.
Keyword tagging for searching and categorization of photos. - Enables Google Maps integration for photos with GPS. - Viewers can 'thumbs up' and 'thumbs down' photos to select the most popular photos using PhotoRank. - Upload from Picasa, iPhoto and other software packages.
Here is a sample with pictures I took at the Great Wall.
