Dr5 lab - reversal processing for a wide range of film. Processes b+w film as positive transparencies:
http://www.dr5.com/blackandwhiteslide/filmreview.html

Provide a unique commercial service for a large number of film types, and top-notch quality too.
I've used them for years and had 100's of rolls processed - always pristine processing. I bundle my orders and send several times a year from the UK - they're that good.
They're a small bespoke outfit and offer excellent help and advice to specific queries about using reversal film.
If anyone wants any other info / feedback please feel free to PM me.