There are a few 40mm enlarging lenses that cover 24x36... Not an enormous gain, though.

http://www.rodenstock-photo.com/en/m...cd/rodagon-wa/
The Rodagon-WA has a shorter focal length and a larger image angle and hence it achieves a 70 % larger projection area than a conventional enlarging lens with standard focal length. It is therefore eminently suitable for section enlargements on enlargers with a relatively short column. Clumsy wall or floor projections can be avoided.

Schneider WA-Componon 40mm wide angle enlarging lens for 35mm and smaller format negatives. The wide angle design provides full coverage of the 35mm format while providing greater magnification compared to a 50mm lens.

See also:
http://www.apug.org/forums/archive/i...p/t-33772.html

Before buying, make sure you can move the lens stage an extra ~10mm closer to the negative stage. Also check diameter, retaining ring.