I researched this on the thread linked by vanflynn. Kanile'a and their Islander ukuleles apparently all have 1 1/2" nut width. I tried out the Oscar Schmidt OU6W (tenor) which has a 1 3/4" nut. The strings are very widely spaced. I liked the instrument, but the nut width seemed almost ridiculous. I've read here that Lanikai has the LQA-C with a nut width of 1 3/4" too, plus a couple of other exotic wood models (zebrawood and monkeypod),in tenor and concert sizes at 1 1/2".
I found one claim that the Koaloha tenor had a wide nut width, but I measured one and it was 1 3/8".
Other than the ones mentioned, I guess most builders will make one for you. Not a lot to choose from, but some very nice instruments, to be sure.