Interface Hall of Shame
Used to support Lotus Notes back in the '90s and enjoyed reading the entry for Notes in the Interface Hall of Shame: Link
One example:
"Judging from the number of visitors who have mentioned it, the process of copying messages in Notes is perhaps its worst interface "feature". Apparently, when mail messages are copied from one folder to another, the message itself is not copied; Notes creates a "reference" to the message. Unbeknownst to the user, if you delete the reference, Notes will in turn delete the message itself. Similarly, deleting the message will cause all references to it to also be deleted.
A number of visitors described the loss of valuable information through this process."
