I just received and read through WotC's 2006 supplement d20 Critical Locations for the d20 Modern RPG.
This was the final d20 Modern product that I didn't have, and while I'm not sure if it was the very last book for in that game's eleven-product run, it feels that way to me since I took so long picking it up. It was essentially a shout-out to Christopher West, who by this point had made a name for himself with his "Maps of Mystery" from Dungeon magazine. Here, we have around thirty maps for various modern locations in the same style, along with write-ups.
I have to take a moment to praise the layout here. Each map is given a whole page, and the facing page provides an overview of the location, including a basic description, the hardness/hit points/break DC for various items found there, (usually) an NPC stat block, adventure hooks, and (usually) some new rules associated with the place. There's even a new spell there...or at least, new to d20 Modern, that being the bless water spell (i.e. to make holy water). There are one or two cases where the map is a two-page spread, and the aforementioned overview is likewise two pages long.
Overall, it's a book that marries practicality with aesthetics very well, and manages to expand on the Modern d20 rules quite nicely as well as being a great resource for locales for adventure. Given that, I'd say that this was a high note on which to sunset the game.