I've always wanted a Waterman C/F, and I finally found this lovely gold-plated one at Fountain Pen Hospital. The C/F hit the market in 1953, while this one's a 1972.
It stands for Cartridge Fill, and was the first successful pen to use a drop-in cartridge, instead of drawing up ink out of a bottle. I've always wanted one because I think the inlaid nib looks good. The pen was designed by Harley J. Earl, who was more famous for styling cars over at General Motors.
You can't buy C/F cartridges anymore, but fortunately, this one came equipped with a converter, which is hard to find. Even it's an oddball thing, with a rubber tip and squeeze mechanism. The pen works quite well, too.
You can find out more about the C/F over at Richard's Pens.