I almost got to use OS/2 for a commercial project.. we had fetch information from a PC desktop and feed it to an IBM mainframe while servicing up to two simultaneous users.
OS/2 1.1 EE had EHLLAPI support but was still a few months from release and I couldn't wait for it. I was really disappointed I didn't get to explore it fully because first look was really impressive.
I ended up using DOS + DESQview, and it worked out fine.