Concept Albums

The Wall is my favorite concept ever. Still amazes me.

:kickass: cheers to Mr. Waters
 
A sign of good concept album: removing the concept from the lyrics would weaken the album significantly. I don't feel that the concept adds a ton to MAYH or Still Life. Change the lyrics, and these are pretty much just as good. These are just albums that tell a story.

An album like Dream Theater - Scenes From a Memory really is a good example of how outstanding a concept album can be. It's really, really good, despite all the fanboys and losers who gush over this.
 
I think lyrics aren't essential to the success of a concept album, but if done correctly, they do add something extra. They allow the listener to really identify with the exact feelings of the protagonist in the story, which music can lack.