Is there any list of all symbols/characters you can use in the Minecraft chat?
Minecraft officially supports ASCII characters under 0x80. It can render more characters, but they do not render correctly.
The supported characters are listed below.
You can find this list together with more info about the possibilities( colors, and style) of the chat at the Chat article on the MinecraftCoalition wiki, if figuring out what these characters are is too much trouble.