I was wondering if the color of buffer shadows (i.e. no raytracing) can be altered, in the way that for example specular color can? It is a common feature in many 3D programs, but I seem unable to find it in Blender.
Not directly, but you have several possibilities. The most flexible way are probably compositing nodes. See Image 1, the setup should be pretty much self explanatory (even if you don’t understand german).
http://de.wikibooks.org/wiki/Blender_Dokumentation:_Farbige_Schatten
Regards
I am fluent in German, so I will enjoy that link very much, thanks!
I was thinking along those lines (now I don’t have to think nearly as hard, of course:)), but it would be neat if it got built in as a fully-fledged feature. I got a juicy tip on some very advanced tricks for producing mist effects, which were also a matter of knowing how to use the compositing creatively, and in the same way, I feel that making such ‘tricks’ standard available features in Blender would be relatively easy (compared to producing new features from scratch, that is) and would be a HUGE boon to the program.
We can do the stuff. It would just be nice if we could do it faster and easier:eyebrowlift:
EDIT: Just noticed the devilish trickery using negative colored lights. I will enjoy this page of Deutche Tricks very much 
Well, we can already make Nodegroups, and then you can append one of those from another file and it’ll show up in your node-add list under Groups . . .
Probably could use a bit of interface to order, toggle, and label inputs, so you can make your group’s API the way you want it.
Ah, yes, and this is the point where I shudder to think of the work that might be involved in my shadow projects (and that just sounds wrong, doesn’t it?). Are there any good tutorials out there on Nodegroups? They are yet another piece of Blender that I have yet to truly touch upon.
As far as I know, the only thing about nodegroups, is that you select a bunch of nodes and then pick “Make Group” from the menu; and then you have one big node with the inputs/outputs of the whole node string you selected, with a little button in the corner that opens up a little pocket-space window where you can get to the nodes inside.
Hmm… guess its trial and error time for me then 