I'm a tcler since 1996.
My contributions to tcl were the patch to add touch functionality to file atime/mtime (1999-10-28, tcl 8.3b1) and the possibility of setting permissions symbolicly (2000-01-12 tcl 8.3b2).
If you want to add info to your MP3 files, Tagging MP3 Files might simplify this task.
Are static variables a must for your app? Take a look at Static Variables