I don't currently use that many modules, because i fancy security and many modules that i would needed for this and that weren't that secure, and most cases just as lazy person i am, i wrote the whole code part myself. only in last resource i start fixing or changing thigs to way i like them on ready made modules, when i can't find or there isn't enough time/lazyness to start learning that. but what i have just browsed i have noticed there are lot of good modules out there, but i just haven't got time to start checking them out.

here are currently what i have used for this/last year often.

CGI = only used it for multipart forms, until i got some time to read more about their used format.
Digest::MD5 # always for passwords.
File::Copy # just to keep me from doing it without copy/unlink style.