A good functional molecular editor is of much important to the chemical web. There are a few small download sized editors around. JChemPaint has been available as applet for some time now, but the download size has been large. The situation has improved considerable over the past months, and the download size upon which the applet now shows up in your webbrowser is down to 538kB. A live demo is available from www.chemistry-development-kit.org.
The applet, however, does have the same functionality as the full application. When a feature is used that is not available from the jars downloaded first (which make up the 538kB), additional jars are downloaded.
The applet is not bugless yet. For example, drawing reactions does not seem to work :( But, it's really getting somewhere. Congrats to the applet development team!