Thanks coreplayer,
I had checked tce-ab for (K)eyword 'screenshot'. I had seen all those entries but, I should remind that I want CLI-only environment atap (as tiny as possible). It's my goal to have as many utilities as possible without Xprogs and other big-sized dependence-packages. Look, fbgrab does only need libpng while screenshot.sh needs Xprogs, and the rest need lxde, gimp (which needs X), qt, totem etc. Install Xprogs just for a screenshot utility? Ew.
Now I have built fbida to have framebuffer only image viewer with no need in Xlibs or Xprogs or something. It needs: libpng, libtiff, libjpeg-turbo, libexif, giflib, fontconfig and some fonts package. It's able of zooming and even editing pictures, vieweing PDF documents (have not tested yet) and is pretty tiny, hey. I'll send them altogether, mp3blaster and fbida I think. And maybe fbgrab too. Just gotta make them clean, stripped and nice.