If you are using Windows you can put a shortcut to the Character Map on your desktop for easy access. That way you can select any character and cut/paste. It will also show you the 4-character codes for those other occasionally useful special characters like: £, ¼, ½, ¾, ¢, ©.
You can find the Character Map in Start > Accessories > System Tools in XP. Right-click on Character Map and select Send To > Desktop as Shortcut.
In Win7 or Vista, click Start and type "charac..." When Character Map shows up in the list, right-click it and select Send To > Desktop as Shortcut.
When you click on a special character in the Character Map, if you look at the very bottom (status) line, at the far right end you will see, e.g. "Keystroke: Alt+0176" for the degree sign.