Restricted File Creation for particuler pattern

HI All, I have this wierd requirment. Any help will be appriciated.

I need to restrict file creation with certain pattern. Suppose, i want my system not to allow creation of files with *.exe extension. The requirment is that file should not be created like it happen in windows you can't create file with name "com, lpr etc etc" same thing i need in unix/linux..i want to create a rule saying that this system will not accept any file name ending with *.exe and *.txt.

Please advice..