There are many more professional CD-i's then there are consumer ones; I don't think a comprehensive list exists.
They range from in-house educational to technical demonstrations and anything conceivable in between.
Such CD-i's would often be just a component of a system and it would not be immediately recognizable as a CD-i except to technical people.
Some samples from the Dutch market:
- The Dutch drive permit organization "CBR" used a CD-i based system for the theory exams for the latter half of the nineties (this replaced a dia/casette player based system and has itself been replaced by a PC-based system). This was coupled with custom hardware to allow a single CD-i system to handle many tens of exam candidates; it was also coupled with a networked PC to handle certificate printing and central registration.
- The Dutch national airport for several years used a CD-i based system for their "Apron Safety Test"; it was a video-based test that drivers had to pass before being allowed to drive their vehicles onto the airfield (between the planes). This used a room of CD-i players that reported the test results of their individual users to a central PC that handled certificate printing and such.
- There was a disc called "Energie Potentieel Scan" that supposedly helped people to achieve energy conservation in their homes; I'm not sure of the distribution mechanism but it was probably freely distributed to the customers of some energy utility company.
- SPC did an Internet demonstration disc for Philips that served as a proof-of-concept of Internet on CD-i (it used a CD-i port of parts of the BSD-Lite TCP/IP stack and simple custom web browser).
- Remeron was a CD-i on antidepression medication that was used by medical salespeople, using portable CD-i players.
- Baxter had a CD-i on diabetic self-help (in several languages) that were on public display or for patient use in several hospitals.
- Philips had a "demonstration" CD-i for the full motion system (MPEG playback) that demonstrated the use of play/pause techniques including slow motion and seeking, as well as more exotic techniques such as window manipulation and seamless jumping (the latter very rudimentally).
- Lots of CD-i players came with an introductory disc on the CD-i system (not sure if this qualifies as "professional", though...)
I'm sure I could dig up others; but this should be enough to give you the general idea.
A large list (but by no means complete) can be found on the ICDIA site
here.