Insert Unicode v1.3resigned1
If you want to use Unicode characters on web sites then you usually have to copy and paste them in. With this add-on you can just click on a button, type in the Unicode value (eg: 20AC for the Euro symbol or 03C0 for the lower case Greek pi character) and click on the "Insert" button to enter the character.
Limitations:
1) Characters will only be inserted in to <input> or <textarea> elements.
2) Only Unicode characters supported by the font will be displayed correctly.
Known Issue: Some versions of Firefox do not auto focus the input field properly.