Editing
These are some general guidelines for editing on this Just Solve the Problem Wiki. Since a wall of text is less likely to get read, these are a relatively small set of hints or suggestions for working on the various entries.
Enumeration is more important than Beauty
The primary concern is missing out on existing file formats, and having no entry for them. Therefore, the priority should be to track down and acknowledge the existence of these formats, instead of slaving away making a well-known format's entry as beautiful as possible. This priority over beauty also exists when discussing where a file format goes - it is much easier to decide to shift a format from one list to another than to know that format ever existed.
Electronic is more important than any other
The primary focus of the Wiki are electronic file formats, as those are the most fleeting and most likely to be non-evident. It's good people are thinking out of the box and adding a range of other formats, but if you're into your tenth hour of describing boat flags and hieroglyphs, perhaps some attention to the more online-oriented entries would be appreciated.
What a good Entry should look like
A good entry for a format should ultimately have, where possible: A short description of the format (created anew, not copy-pasted from another source), a link to an example of that format, links to other listings of that format, links to any web pages about that format. Ultimately, it would be good to have code for reading that format, but unless that already exists, then it may be something that comes later.
Cross-Linking is your Friend
Use lots of cross-linking in the entries so that related items that aren't necessarily connected otherwise (say, Filesystems to Floppy Disks) get those needed connections. Which leads to the last suggestion.
Remember Who This is For
Ultimately, this wiki will be of the best use to people who either know something is a file format, or who are trying to determine what possible format this file could be in. They might know it was made by some application, or that it has a certain file extension, or that just that the file was on a floppy disk from 1983 next to some machine called a PET. When putting together entries, remember these people; they're the ones who need this most.