separating files based on its extension

I am a bash newbie, having difficulties making some script. I have some directories containing filez with many extension. I want to separate those filez into new directory on the filez' directory and name the new dir as the filez' extesion. I wonder to know how the bash script look like? For example, /foo/a.pdf moved to /foo/pdf/a.pdf /foo/a.s.zip moved to /foo/zip/a.s.zip /foo/a.b.123 moved to /foo/123/a.b.123 ad so on Thx in advance. -- --- hart