Been testing several Japanese games (One game at a time) and used Google Translate app on my phone to translate the text using the Camera. Not always perfect results but with some guesswork it makes isolating each game's potential net features a lot easier.
I'm not finished by any means, but there are already a few outlying oddities;
Battle Beaster - had a DLC mode and/or leaderboard event "coming soon" that never ended up coming out.
Dancing Blade: Kattani II and Imperial Fighter of Zero are not VGA compatible, as they wouldn't show a picture on my TV past the DC boot logo. A shame, as I don't think I have a way around this flaw. There may be more like this, but I'll mark them as I find them.
Guilty Gear X - Had no idea what this was. Pleasantly surprised to find a 2D Fighting title with online Leaderboards.
Lakemasters Pro - I can't find the website. The game browser uses http://www.lakemasters.com
(then is cut off and can't be read) but this turns up nothing on Wayback Machine. Likely lost.
Love Hina - Doesn't have a browser, nor multiplayer, nor voice or leaderboards or DLC. It's online connectivity is specifically to send emails/download emails from characters from the game. A strange attempt to continue a romantic relationship with the characters once the game is complete?
Milky Season - Despite having a website, and the box stating it is Modem compatible, I didn't find an option for the browser to view the site. The site only has game info anyway, but even stranger is this title appears to have lots of DLC on the disc ready to save to your VMU - even for games that aren't Milky Season (but presumably by the same publisher/company). If you are into your visual romance novels, then there's DLC on this disc for Milky Season, Memories Off, Never 7, Close To, Yume no Tsubasa and Tentama. The strange thing is most of these games have browsers on disc, but no DLC on the sites. Perhaps this was an attempt to strongarm people into buying a new game disc? Very odd.
Net de Para - Mario Party style game. Might be interesting to be translated. Allows for online play.
Roommania #203 - What the hell is this game? Seaman is pretty crazy, being a game where you raise pet fish who talk to you. But Roommania is a "life simulation" game where you live in a small flat with a man and have to throw balls around the flat to either annoy or placate him. Who's life is this meant to be simulating? XD
I'm up to Segakara for Dreamcast, Shinri, Spawn: In the Demon's Hand, Sports Jam, Tantei Shinshi Dash and Treasure Strike.