benfry.com/traces/

The Preservation of Favoured Traces is a Processing based applet that visually displays the differences between various revisions of Darwin's Origin of Species.

benfry.com/traces/

chir.ag/stuff/sand

The Falling Sand game has been around for a while, and allows you to create paths, structures and flows from 4 falling sand elements. Simple, but oddly addictive.

http://chir.ag/stuff/sand/

www.wefeelfine.org

An applet that visualizes current global emotions by scanning blog entries and tweets for occurrences of "I feel..." and "I am feeling...", then displays then in a dynamic cloud that can be filtered by a variety of criteria.

N.B. Doesn't seem to like running in a browser with the next-generation plugin features enabled - I had to switch them off for it to run successfully.

www.wefeelfine.org

www.bitlet.org

Bitlet is a browser-based video player for BitTorrent files - so you can stream torrent videos and watch them in your browser, rather than waiting for the whole file to download.

www.bitlet.org

www.thinkfree.com

ThinkFree is an MS Office compatible applet-based office suite, allowing you to create and open documents and spreadsheets without installing any software.

www.thinkfree.com

www.neoformix.com/Projects/TwitterVenn/view.php

The Twitter Venn applet allows you to enter 2 or 3 search terms and searches Twitter for matches, then presents the results as a venn diagram, which illustrates the rate of tweets containing the search terms in the various combinations.

http://www.neoformix.com/Projects/TwitterVenn/view.php

koolpianoz.com

This applet allows you to play the piano and will accompany you on different predefined songs.

Needs Java 6 to run properly.

http://koolpianoz.com/