Applets

Akmin Editlet
Applet based online HTML rich text editor. [Commercial]
http://www.editlet.com/

Anagram Generator
Java applet which will anagram user-entered phrases.
http://freespace.virgin.net/martin.mamo/fanagram.html

Analyze - Text analyzer
A specialized tool for examining one or more texts. Texts are sequences of elements, such as bytes, characters or words.
http://www.cvkimball.com/Analyze/Analyze.html

Aniyog - Applet Gallery
Two applets: One is for kids which makes learning alphabets and numbers easier and other is for Choosing colors for Java GUIs and web pages.
http://www.aniyog.com/java/applet_gallery.htm

Anything 3D Imaging Solutions
Anything3D Glide Menu (java applet can provide any website with a professional looking navigation system, create a text-only menu, or combine both text and images together), Anything3D Presentation Applet (new interactive tour for image which allows to view presentation over the internet without requiring the use of plug-ins which take forever to download), Anything3D Pano Viewer (an exciting new panoramic viewer which allows web surfers to view panoramas over the internet instantly).
http://www.anything3d.com/product/webutils/

Color and Font Chooser for Java and HTML
Lets programmers choose and try out different combinations of foreground and background colors. RGB to hex and vice versa conversion can also be done. One can also try out different fonts. By Ashok Kumar Gupta.
http://www.akgupta.com/Java/ColorChooser.htm

dtzTech
Applets and source code, including 3D rendering and vocabulary quizzing tool. Also forum and email service.
http://www.dtztech.com/

EditLive!
Browser-based HTML editor applet for WYSIWYG content authoring. [Commercial, online demo after registration]
http://www.ephox.com/products/editlive/

Java Calculator by Entity
A page for my java calculator applet.
http://www.geocities.com/entity05/java/myjava.html

Java Filter
An utility that lets users take control over which applets they want on their system. By SIP, Princeton.
http://www.cs.princeton.edu/sip/JavaFilter/

Java Financial Calculators
Financial Calculators you can put on your website. Colorful, interactive, graphing financial calculators.
http://www.javacalc.com/

Java Multiple File Upload Applet (JUpload)
Takes care of the limitation posed by traditional HTML upload forms by allowing upload a whole directory and the files within it with a single click. [Open source, GPL]
http://jupload.sourceforge.net/

Java Simple Regular Expresions
Applets reads simple regular expressions and builds a state machine that recognizes regular expression. Provided source code is appropriate for educational purposes.
http://www.oursland.net/projects/regexp/

Java Upload Applet
HTTP and FTP upload applets for uploading multiple files to a web or FTP server. [Shareware]
http://www.javaatwork.com/

JMessenger.com
Provides instant messenger services for websites. No software installation necessary.
http://www.jmessenger.com/

JUpload
An applet for uploading multiple files to the webserver at once using the post method. Online Demo. [Commercial]
http://www.jupload.biz/

Polynomial regression analysis applet
It calculate a calibration for a MALDI TOF (and possibly other) mass spectrometers using any kind of (semi-)repetitive peptide as the calibrant.
http://home.scarlet.be/yvan_martens/rug/RUGApplet.html

RealObjects Edit-on Pro
A WYSIWYG editor applet. Provides word processor-like features, like a spelling checker, for XHTML markup creation.
http://www.realobjects.com/

Reystar Coolbanner
Takes any number of banners (468x60) and rotates them in order using different cool transitional effects to hide one and display the next. Highly configurable.
http://www.reystar.com/java/coolbanner.html

Sferyx JSyndrome HTMLEditor Applet Edition
A visual HTML Editor Java applet. [Commercial]
http://www.sferyx.com/htmleditorapplet/

Stock Market Java Applets
Stock market quotes and tickers Java applets. [Commercial]
http://www.stockapplets.com

Sun Microsystems - Java Applet Security
Article on commonly asked questions regarding Java Applet Security.
http://java.sun.com/sfaq/

Synth
A Java program that can be used to generate sounds. You design the sound by putting together basic building blocks (generators): oscillators, envelopes, adders. Once the design is done, you instruct the program to generate the sound (which can take some time, depending on the complexity of the sound).
http://www.epiphyte.ca/code/synth.html

Teutoburgo - JaVi (Java Vigenere) Applet
Contains an open source Java Applet called JaVi (Java Vigenere, Vigenere is an algorithm for cryptography). Includes manual (including UML diagrams and Javadoc documentation) and standalone version.
http://teutoburgo.web44.net/java/indexJavaEn.html

Thompson, Nathanael
Mandelbrot viewer and chemical engineering Java applets (with source), a forum and chatroom, resume.
http://www.geocities.com/ntgt13/index.html

Wibbleware
Menu and banner applets. [Commercial]
http://www.wibbleware.com/

Wyka-Warzecha Say-It-Now
An applet that allows you to add speech synthesis to your website (not streaming audio). Utilizes concatentation method, formant synthesis being developed.
http://www.say-it-now.com/

Yodel - Java Demos
Swedish demo group.
http://yodel.net/old/java/java.html