I'm pretty sure the only record that was just FOB was Evening Out With Your Girlfriend. And well, if that's what you want your musical taste sucks.
I wasn't aware of the guests on TTTYG or FUCT until this thread, actually. My comment is just because I've been aggitated at Fall Out Boy's more recent guest spots. Some are completely needless -- case and point Jay Z's. It served no purpose. The only reason why, was because they wanted to hype up the fact that Jay-Z would appear on the record. Same with Elvis Costello, Lil Wayne. The contributions these people have are far outweighed by the potential of the songs if Fall Out Boy just left it to themselves. These guest spots are not a collaborative effort whatsoever, it's Fall Out Boy adding bells and whistles to appear more progressive or more a part of something they could achieve on their own.