Um, yeah. Instead of authenticating to Yahoo or Slashdot, I suggest you authenticate against somewhere like PayPal or Charles Schwab. At least that way you've got some chance of recouping your investment of time and energy.

Seriously though, this seems both insecure (who's going to send a username/password from one service to authenticate on another?) and pointless (it's not all that difficult to learn how to use crypt or Digest::SHA1 or whatever). Can I ask what do you hope to achieve with this scheme?