Yes, I use my 3DS browser too! I'm also on NSMBHD, which also works on 3DS. Except that you cannot edit very much of your profile because the tabs of the NSMBHD edit profile page don't work on 3DS. But you can just PM Thierry and she will make the edits to your profile like real name, birthday, location. Just PM Thierry. She edited my profile too. And I also lurk on Amino and Bulbagarden, but they require an email address to register, so if that's not your thing... oh yeah, and GBAtemp! That site's all about modding, emulation, hacking, homebrew and overall gaming too. Other sites that still work on 3DS: NintendoLife, Time Extension, TCRF, PokémonDB, IGN, Google, SuperCheats (but that one's a little overpopulated by n00bz), Stack Exchange... I might come across more. Reddit only works for like 10%, so don't go there.
And yeah, that "white room glitch" is really a 3DS browser thing, just like images not showing up half of the time. To fix it, either refresh or click Home (the Home link on this site, not your 2DS's HOME button).
LE EDIT: I forgot about The Cave of Dragonflies, a Pokémon-related weblog with a board. Try The Clue Game, it's really hard, but really fun! But I warn you, for clue 3 you'll have to sit through the Marquee of Doom - prepare to be wasting about an hour (half an hour on PC, but 3DS browser is slow) of your life you'll NEVER get back! (If that emoji doesn't load on your 2DS, go to NSMBHD and then return to here.)
And Kafuka (SMB3 hacking board), StrategyWiki, Know Your Meme, The Pokémon Factory (really old) and Github also work on 2/3DS. And I know Arisotura will be really mad about me mentioning Skelux's homepage, but it does work on 3DS. Oh yeah, and the online Blender manual, but that's only relevant if you use Blender.
And yeah, that "white room glitch" is really a 3DS browser thing, just like images not showing up half of the time. To fix it, either refresh or click Home (the Home link on this site, not your 2DS's HOME button).
LE EDIT: I forgot about The Cave of Dragonflies, a Pokémon-related weblog with a board. Try The Clue Game, it's really hard, but really fun! But I warn you, for clue 3 you'll have to sit through the Marquee of Doom - prepare to be wasting about an hour (half an hour on PC, but 3DS browser is slow) of your life you'll NEVER get back! (If that emoji doesn't load on your 2DS, go to NSMBHD and then return to here.)
And Kafuka (SMB3 hacking board), StrategyWiki, Know Your Meme, The Pokémon Factory (really old) and Github also work on 2/3DS. And I know Arisotura will be really mad about me mentioning Skelux's homepage, but it does work on 3DS. Oh yeah, and the online Blender manual, but that's only relevant if you use Blender.