There was one in the basement of the science building at a university I went to on the west coast. It was very popular. There were a couple of attempts to seal it off, but the blockages were always removed within a month. Interestingly enough, it was apparent the gloryhole was created using a power tool, so maybe it was one of the custodial staff who first created it.
I've seen lots of peepholes in public washrooms as well. Two that come to mind are at a mall in the upstairs washroom, and between stalls at another university I attended on the east coast.
There is a adult store in my city that has a back area with gloryhole booths. I've always been curious, but not that curious. There is a difference between blowing a student between classes, and blowing a seedy regular at a sex shop. I suppose if you prearranged a meeting with someone it would be hot, but I couldn't risk it with some random dude, especially with the spike in STDs these days.