The topic says it all... Im using an almost identical way to print out fonts as in NeHe #14, but i can't change the height of the fonts. This dosn't work with the full code for tutorial #14 either... I can change size by using glScale(), but this look terrible when scaling down to small sizes... However if I use #13 all is great and the height behaves nicely. Is there anyone who can explain why changing the height with fonts created with wglUseFontOutlines() doesn't work, while it does with wglUseFontBitmaps()?

As you mentioned, you can use glScale with outlined fonts, so there's no need to use font heights.
In fact, outlined fonts have rather some normalized space, which makes it much more convenient to integrate into a 3D environment.
Bitmapped fonts are in essence aligned to pixel rasterization, so you need some height parameter other you would have to use glPixelZoom or such functions which really looks crap.