The glass covers the entire top except for about 3 - 4 inches in the back which I have covered with those plastic "slip-on" strips that attach to the glass. I just cut the openings I needed for my skimmer, canister, etc but did not leave any room for anything to jump out.
I'll show my ignorance here and just say I'm not positive what you all mean by "eggcrate". Is it something I would purchase at the lfs
or at HD
I also have a wooden canopy that matches my stand so I don't really care what it looks like under there.