Proper knäckebröd is rather dry for "all the breads in the world", but most definitely not tasteless, like cardboard is.
Some variations are - at least if you are used to a more tasty one. We used to argue about näkkileipä (as it's called in Finland) with one of my friends at school since we had two variations of it in the school canteen and both preferred a different one. I used to call the one she liked pahvinäkki, "cardboard näkki", since imo it was tasteless and chewy compared to the other (which she in turn called snobinäkki, "snob näkki").
In Finnish and Swedish shops there's usually a whole row of shelves full of different näkkileipä and other "dry bread" like hapankorppu, "sour cracker", which is a really yummy thin rye cracker. My favorite näkkileipä is a rather crumbly one covered with pumpkin seeds.
Edit:
Here is a Finnish receip for Helppo näkkileipä, "easy näkki bread".
Ingredients:
2 dl water (or milk if you like)
1 teaspoon salt
100 g melted butter
4 dl rye flour
2,5 dl wheat flour
sesam seeds or poppy seed if you like them
(you can also add herbs or spices if you like)
Mix the salt and melted butter in the lukewarm water. Whisk the rye flour in and knead the dough adding the wheat flour. It should turn out elastic and easiy to roll out.
Roll out the dough into a thin slab, about 3 mm thick. It's important that the thickness is as even as possible all over the slab. Sprinkle sesam or poppy seeds all over the slab while rolling it out and roll them into the dough. Stick little holes into the slab with a fork and cut it to pieces either with a cookie form or a
"dough wheel".
Bake in oven in 225° C for 12 - 15 minutes untill the breads have gotten some colour on their surface. Cool down on a grid.
(Doesn't look or taste quite like the versions sold in shops, but nice munchies anyway.)
