In addition to the Antonov 72/74's, Boeing worked on the YC-14 concept as a replacement for the C-130's.
Also, many seaplanes have to place the engines as far up as possible, to keep the engines and propellers out of seaspray. This has the secondary effect of accelerating airflow over the wing and increasing its effectiveness.
The engine wash is also used to increase the effectiveness of control surfaces, an example for this is the A-10. The A-10 blows jetwash between the rudders and above the horizontal stabilizer, augmenting the efficiency of all these surfaces.
The downside is that the surfaces in contact with jetwash need to be designed to handle the soot and extra heat. The airplane also needs to be able to handle the lift imbalance in case of an engine failure.
Not a great example, but good to illustrate I think.