Here are a bunch of extensions that are developed for Firefox.
Extension List
| Name | Version | Application | Platform | Description |
| DictCN | 3.1.3 | Firefox 1.0.*-3.* | All | A Handy Translator for Chinese/English with voice |
| OMusic | 1.5.8.1 | Firefox 1.0.*-3.* | All | An Online MP3 Player with Playlist & Lyrics |
| GB2Big | 1.2.1 | Firefox 1.0.*-3.* | All | A Translator for Simplified/Traditional Chinese |
Page on addons.mozilla.org
| DictCN | https://addons.mozilla.org/en-US/firefox/addon/2082 |
| OMusic | https://addons.mozilla.org/en-US/firefox/addon/4617 |
| GB2Big | https://addons.mozilla.org/en-US/firefox/addon/4559 |
The version of these above extensions on official site may be outdated. You can always download the latest version here at Featured Downloads
The source code can be download at the Source page