This is by no means an exhaustive list. Plenty of cooking and recipe websites have sections for regional cuisines that aren't difficult to find, but I sought for original blogs in English. There are plenty of regional cuisine cookbooks as well, so do not feel limited to the internet (is that a limitation? I wonder...)
HungarianThe Hungarian Girl is a travel/food guide as well as an excellent source for recipes and a Twitter friend!
Hungarian Food Guide is a good resource as well.
PolishSo Much Begins With A Meal - Polish cuisine, complete with recipes.
Polish Food and Recipes isn't winning any design awards, but it's solid.
Coffee and Vanilla
Anula's Kitchen is definitely original and features a lot of Polish food.
Czech/SlovakMy Favorite Czech Recipes may not be the prettiest looking, but it delivers on content.
Czechmate Diary is not strictly about food, but she has a label for all Czech/Slovak recipes.
Slovak Cooking is entirely devoted to food and found through this Pinterest board, which has a good selection.
SlovenianSlovenian Roots Quest is not a strict food blog, but the link takes you to a list of recipes, which can be found on the blog by using the search bar.
Culinary Slovenia (the English sister site for Kulinarika) has a wealth of information.
RomanianMoments Sweet and Fragrant (Clipe dulci si parfumate) was among the 36 blogs I found listed here, though mostly in Romanian.
In Bucatarie Cu Tata (In the Kitchen With Dad) has a decent selection as well, though I'm not sure if it's strictly regional.
CroatianBite My Cake is a bilingual food blog that is adorable (and she writes the column for Honest Cooking below).
Essence of Dubrovnik is a mixture of food documentation and recipes, which gives a fun voyeuristic vibe.
T and T Kitchen Atelier is in Croatian, but the translation function works great.
Croatian-English Parallel Corpus of Recipes is an interesting blog since it's half folklore project, half recipes.
Old Time Cooking Recipes does have a decent Croatian cuisine tag.
BosnianI didn't find much, sadly. I found a few featuring Bosnian recipes, but nothing close to some treasure troves I found elsewhere: Gourmandize and Travel by Stove
SerbI Love Serbian Food is pretty explicit in its content. Serbian food and lots of love.
Food for Thought is bilingual and has a great breadth of content
MontenegrinMost of the blogs I found were putting Serbian and Montenegrin together.
MacedonianSitnoseckano grew into its own website, from its humble blog beginnings.
My Macedonian Kitchen is a lifestyle/cooking blog when the author was living in Macedonia.
Macedonian Food, Cuisine and Recipes is straight with only recipes.
AlbanianI didn't forget this country, but food blogs seem to have done so.
BulgarianAngel Love's Cooking is already bilingual, but it does provide a translating option, which I love.
UkrainianNatasha's Kitchen is beautiful and the food looks amazing.
Claudia's Cookbook has a delightful selection to drool over as well.
MoldovanHealth Cooking is a mixture, but heavily features native cuisine.
LithuanianSurfing the World Cuisine - an interesting mix of Turkish and Lithuanian cuisine
LatvianCooking In Latvia is a work in progress, but it looks promising as a resource.
EstonianNami Nami is not strictly an Estonian cuisine blog, but she does have 175 entries for Estonian food, found easily with the post label. (Side note: doesn't this kringel look fantastic? Contrary to what the website says, the blog is Romanian and doesn't feature much Estonian food)
BelarusianMy Native Belarus doesn't give much, but most blogs were light on the cuisine.
A Global Garnish featured very few and Our Food Recipes provides some links.
ArmenianThe Armenian Kitchen
AzeriAZ Cookbook: Food from Azerbaijan and Beyond - a mix of everything, but more focused on Azeri food
GeorgianDelicious Georgian Cuisine
RussianRusCuisine.com: Authentic Russian Recipes, Cuisine, and Cooking - possibly most excited about this because I've been wanting to make zakuski
All-Stars aka Featured Almost EverybodyFood Perestroika: Adventures in Eastern Bloc Cuisine - probably going to be a favorite for any pan-CEE food lovers
Palachinka covers Bosnian, Bulgarian, Croatian, Estonian, Hungarian, Macedonian, Serbian, and Slovak, though not necessarily in large quantities.
About.com does not have a bad page for eastern European cuisine, so I suggest checking that out as well.