As you can see in right column, you can search along this web. Just write something in the input field and press button Find it. It has also some not too apparent features that this page is describing.
Looks over all articles. Besides normal search you can also use following constructions:
Looks for given keywords assigned to article. It is usually places and persons connected with the action. There is overview of all keywords - Tag Cloud.
Look for images using their descriptions or keywords. As for articles there is also Tag Cloud. And similarly it allows some special constructions:
Pic of the day
What is this