Although, for someone like myself (tedious and shy of making definitive statements in concern of mostly arbitrary and heavily opinionated "polls") this did seem like a really good thread for discussion and debate, but it looks like it never made it very far from the OP's list. A few additions were made, but I am going to *bump* this in hopes of reading a more extensive, diversely opinionated list.
I think that it is important to distinguish between an album that has been over-hyped by the media for their own purpose or gain (I'm not so sure there is a difference between the two), and an album that is genuinely considered to be overrated due to a number of other logical reasons. To name a few: The bands preceding success, listeners unwillingness to let go of nostalgic feelings for the band (and thus not rightfully taking new listeners to the same level), and/or a severe lull or currently ebbing/transforming music scene. The latter is certainly fewer and farther apart (IMO), but I have felt that I experienced such a time just as recent as the years between 2000-2002. But still, the latter is a bit arbitrary.
Alas, my LIST (In no certain order)
1. Hotel California - The Eagles (This goes under my Nostalgia reference)
2. The Black Album - Metallica (This is unique, both the media ate-it-up, and the bands preceding, great efforts yielded their highest ever record sells, and made them a house-hold name). Still, the album sucked and developed an unfolding stigma the band never seemed able to shed).
3. Follow the Leader - Korn (I'm too tired to even explain myself here... The nostalgia thing, but to a lesser degree).
P.S
To he or she who said Tom Waits album Rain Dogs is overrated - Sounds to me like a personal problem, rather than a discerning observation in regards to the OP's request. I really can not think of any other logical deduction to reach such a conclusion. As always, this is just my opinion...