I have built a small web application in PHP where users must first log in. Once they have logged in, I intend on showing a small thumbnail as part of their \"profile\".
I recently saw this tip's list: http://www.ajaxline.com/32-tips-to-speed-up-your-mysql-queries
Tip 17: For your web application, images and other binary assets should normally be stored as files. That is, store only a reference to the file rather than the file itself in the database.
So just save the file path to the image :)