Like The White Album. 'This is such and such a bands white album'. Usually it means an album that is long and shows a band experimenting within a wide variety of styles. Often it is made during the later stages of their career, when they are less hung up about creating the perfect record. The album does not have a cohesive theme other than that of variety and experimentation.
Be Here Now. 'This is such and such a bands Be Here Now moment'. Usually it means a band following up a critically and commercially succesfull album with a self parodying failure. Usually the record is over produced and lacks strong material at its core. Usually the record has the atmosphere of a last piss up before the ship sinks. Usually copius ammounts of Cocaine are consumed during its making.
Kid A. 'This is such and such a bands Kid A'. Kind of the opposite of a 'Be Here Now' really. Usually it involves a band following up critically lauded album with another critically lauded album. Crucially though, the band experiment and take a left turn that surprises everyone. Unlike a 'White Album' though, the album will have a cohesive feel. Often electronics are involved.
I don't think there are any more album titles that have enetered the lexicon of rock and roll like the above three are there? If not, please suggest other albums that have been seen as a bands 'white album', 'be here now' or 'kid a'.
For example, 'wowee zowie' by pavement is often described as their 'white album'.