Alright, I must come forth and say that Ive been working to develop these programs I have mentioned, mainly in theory, sometimes in actual code.
As for my solution to tools like cutscene maker etc, I always try to make them as modular and straight forward as possible, and try not to limit the user in any way.I guess the solution was somewhat revolutionary for me at the time;
Write our own file formats. Using the file_str/var commands it can be easily done. For the cutscene maker, not only did I want to be able to interpolate the POS' and ANGLES, but I wanted to give the user the ability to interpolate everything else as well, ARC, ASPECT, TRANSPARENCY, etc.
The only reason I never released these tools is because there is a bug in my interpolation code. Not always, but everyonce in a while, the camera will do the wrong thing. Here is the problem;
Since its KEYFRAMES that are used, my code resolves the direction to travel on a given axis as being the shortest of the two directions to the next keyframe's pos/ang. This works fine if the animator understands that, but in the case where POINT B is farther away in the intended direction than in the opposite direction (think rotation), the object would simply take the shorter direction(go the other way), which is not what was wanted by the animator. Ive tried several different methods, but all have a problem somewhere. For instance, if I dont use ang(); to return wrapped values (-180 to 180) for angles, then Im working with absolute rotational values, and thus the camera/object would do several rotations (spinning) before ending at point b. Its been hard to find the perfect solution. Also, my code is all built on simple arithmetic, and uses functions like:
dist_on_axis = getgaps(sourcevalue, destval);
to always return either 0 or a positive value giving the distance, because you have to manage the fact that the different positions could cross 0 pos/neg threshold at any time.

I am considering releasing some of these tools for further development by myself and others, if anyone is interested in seeing these tools become of real use, let me know. The only real work left to be done on them is to fix the interpolation code so that it always works perfectly.
PS: The other problem with my equation is that it uses distance_per_cycle as speed, and if this distance is not within a certain range, problems can occur; Ive resolved this as good as I know how by manually setting the final position if the distance to travel is larger than the distance remaining.
Also I still need a final smoothing pass where the movement speed is the same over different distanced keyframes within the same animation.