I did one of these for the Dreamcast once, so why not the Mega Drive? I've been on a bit of a high for Mega Drive Japanese games lately, so for those collecting them here is every game released in Japan for the system in chronological order (according to the database over at Guardiana), with their front covers featured which I found from various sources (some games were hard to find the covers of, so the quality of the pictures varies) and some OC Remixes of Ristar and Streets of Rage for good measure.
Funny to think of how many games they got over there that we didn't, yet their game line up is actually missing quite a lot too, such as Vectorman. Many Japanese versions of the games are much rarer, especially most of the games from 1995. Maximum Carnage and Bart's Nightmare can be found here easily and aren't even very good games, yet the Japanese version fetch hundreds upon hundreds of quid. A bit silly, really.
There's something to be said about the boxart from Japan though: there is a lot of nice artwork to be found. Compare the likes of Jewel Master, Alisha Dragon, Strider and others to their Western counterparts, you have to wonder what was going through their heads. Still, there are some odd choices like the cover to the The Ooze, which try to stand out as some sort of newspaper article with no artwork or screenshots, and Bio Hazard Battle goes by the name 'Crying' for some reason. These kind of differences from the west and east don't tend to happen so much now.
A blog you'll want to check out if you're looking to start collecting Japanese Mega Drives would be Mega Drive Memories by Ian Wilson.