I've been looking at getting a lens hood and adapter ring which allows you to fit a 49mm filter. The original Fuji version of this is rather pricey - over £65. I managed to find an alternative, third party one made by JJC. This includes the lens hood and adapter ring. I managed to get this and a 49mm Hoya UV filter for £23.99.
I was very pleased with the price and when I saw the lens hood and adapter ring in the flesh I was even happier. I cold see no discernible difference between this and the official Fuji version. Both are made of metal and the JJC version has excellent build quality.
Some X100 owners may only want the original lens hood/adapter ring on their cameras but if you don't want to save some money, you might want to check them out. I got mine on Amazon.