When I mentioned how I couldn't imagine using the Uniball Signo Bit 0.18mm pen I got the other day, Charles expressed interest, so I sent it to him. Charles wrote an insightful review of the pen on his blog. He had better success with the ridiculously fine point on finer paper than I did with a cursory test on typical American notebook paper, and notes that it seems best suited for very very tiny lettering.