One thing: we’ve just introduced regular expressions in the auto-tagging rules, and maybe you could be interested in giving it a go?

Yes , It’s nice that they are implemented. I’ve already used them in a similar way than in that post and everything went ok. The expressions I used were slightly different-let’s say it’s the same but with "common factors" applied :

.*.(?:doc|pdf|chm|ppt|xls|rtf|docx|xlsx)$

EDIT: Actually I had it beginning with .+. , i didn’t know that Windows allowed files with no name and only extension, but seems it does allows them, so in this case the asterisk is more accurate than the plus sign