http://fileformats.archiveteam.org/wiki/Dendrochronology
http://fileformats.archiveteam.org/wiki/Quantum_computer
http://fileformats.archiveteam.org/wiki/TLD_.mobi
http://fileformats.archiveteam.org/wiki/Endianness
How is any of these things a file format? Because the definition of a file format in the FAQ (<http://fileformats.archiveteam.org/wiki/FAQ:File_Format>) is so broad that it can be made to encompass basically everything. The manifesto that started this site is a rambling sermon that doesn't clarify anything in this respect: it just repeats "let's solve the problem" without even properly defining what the problem is.
There are also other issues. The classification scheme is often Procrustean and confused. Error messages were until recently mixed up with error detection codes, which conflates two different meanings of "error". Similarly FUSE shares a category with HFS+, even though the former is an API, and the latter a disk format; distinct things which just happen to share the name of "file system". The pages are rather short and consist mostly of lists of links. Given the above-mentioned lack of clearly defined scope, I suspect many pages seem to be created about topics just because they're in the news and/or just to have a place to put a link to a "neat" blog post: see for example <http://fileformats.archiveteam.org/wiki/Facebook#Links>.
Last but not least, the whole site is rather ugly, and the logo is awfully non-descriptive of what it's supposed to contain; what am I supposed to do with this thumb, stick it up my arse?
It's a shame, really, because documenting file formats is a hard and valuable endeavour. But I don't think these people are going to do a good job of it.