I dug out my 58mm closeup lenses and experimented today, that was fun; also messed around with the box full of odd lenses I have.
I like the rapid rectilinear for its perspective - I have never fancied fisheye-type wide angles. I have longer focal lengths covered; two 135mm lenses (one is plasmat I think and the other a Cooke triplet) and one symmetrical 150mm process lens (a supersharp one!) but I want something cheap and dirty for the rare occasions I'll be needing a wider angle.