While 'Sign Pen' isn't a commonly-used term in the UK, it is in Japan, and most people have probably heard of a few sign pens. The classic Paper Mate Nylon, often known as the Flair, is a sign pen. Rather more obviously, so are the Pentel Sign Pen and the Pilot V Sign Pen. It's a Japanese term for a felt-tipped pen designed more for writing with than for drawing and colouring (though they can be used for drawing too). They're popular in Japan because the conical fibre-tips can work like a fine and firm brush, making them very suited to Japanese characters; but they're popular elsewhere too, because the same feature can give a bit more character to your handwriting while still being very easy to use. For a more unusually-styled sign pen, try the Stabilo Greenpoint - recycled so it's green, and orange so it's bright and cheerful.