Here's a pen from Sega World London. As you can see, the pen itself isn't Sonic themed (Just silver foil with black spiral) but the base is. It has speeding Sonic and Segaworld in silver. The pen is rather large, so it's mostly decorative. Why? It appears to be one…
This keychain isn't officially Sonic, but it was a part of a Sonic promotion when the Sega Dreamcast came out. You can sort of see the reddish/orange-ish swirl on it.