The are a number of Web sites that promote the display of excellent photographs. Some are general, others are specific, such as pets or specific camera models. You can find a list of sites at the Imaging Resource's list of free POTD sites.
For users of Canon PowerShot cameras, there is a POTD (picture of the day) site, too: p-o-t-d.
All of these sites have specific submission requirements, so be sure to read the rules before uploading your pix.