First of all I'd like to direct your attention to this:
Japan Blog List
It's an aggregate of a huge number of Japan-related blogs, so if you're interested in those (and you must be, since here you are) you sort of owe it to yourself to check it out if you haven't already.
For reasons not completely clear to me, I read an inordinate number of Korea-related blogs. Weirder, my interest in Korea comes from reading blogs, not the other way around. Here are those that I think are most worth your time:
DatinginKorea - The original and still my personal favourite.
Eat Your Kimchi - Young married couple who make pretty hilarious videos. Martina is adorable.
I'm No Picasso - A well-spoken longtime expat who's now taking steps to solidify her place in the country.
Roboseyo - Perhaps the most prominent and definitely one of the most eloquent K-bloggers.
Stupid Ugly Foreigner - Though he no longer lives there, if you like Korea, humour, or just excellent writing, he makes for an awesome archive binge.
Topiclessbar - A self-deprecating, cleverly structured blog written by a very personable American.
Since I know a lot of you are interested, right?
Jisho.org - The single best Japanese-English English-Japanese online dictionary out there.
All Japanese All the Time - This guy is frankly more than a little pretentious and the bulk of his tips are explicitly designed for people who have trouble concentrating for more than five minutes at a time. But the philosophy is dead-on (or at least, I agree with it because it's also my own), and if you can tolerate the irritation he could well prove a great asset to your J-journey.
Japanese for the Western Brain - Clear and engaging explanations of Beginner-Intermediate grammar points. She also used to have accounts of her world travels, which were very interesting, but she seems to have taken them down. If anybody stumbles upon them please please let me know where they are so I can enjoy them again.
Tim's Takamatsu - An assortment of word lists and grammar points with a focus on the little details that solidify overall fluency. Ranges from very basic to universally useful. Even long-term studiers may find something new here.