Make XSD's pretty print available objects.
Use a thesaurus on a whole paragraph at a time.
Post your annotations on top of a site. Good for sharing and makeshift ecards.
Make your very own heatmap. Get creds for kinda looking cool.
Make captchas for more cheap entertainment. Amaze friends that think you really are a computer.
Find the word that has 3 s's with one s on the end of the word.
Practice vocabulary.
Verify the integrity of an address using google.
IE based notepad made with a conglomerate of js libraries. This was built way before jQuery made it mainstream.