Quick Flickr Front End With Ruby On Rails

This video shows how a custom front end to Flickr was created in a few minutes.

Useful (and free) Web Apps

Back Pack is an event organizer web page for a to-do list, photos, text. Free for personal use. Pages may be shared with some users or made public.
To Do List
White Board

AJAX and Google's Suggest

Not only is Google's Suggest an example of using AJAX, it is also a neat way to do a one-word Google search. Start typing the first letters of a word and it will suggest matches. The more you type, the more refined will become the suggested matches.