Whenever I'm pitching use of CTAT, for example, to students in my E-Learning Design class, I want to show some of the great examples of CTAT tutor interfaces that have been developed. The following paper has a great variety of 18 compelling examples in the Appendix:
Aleven, V., McLaren, B. M., Sewall, J., van Velsen, M., Popescu, O.,
Demi, S., Ringenberg, M., & Koedinger, K. R. (2016). Example-tracing tutors: Intelligent tutor development for non-programmers. International Journal of Artificial Intelligence in Education, 26
(1), 224-269. doi:10.1007/s40593-015-0088-2
It would be super if these examples were more directly available
from the front page of the CTAT website!