"This writer writes in an interesting way."
Translation:Ten pisarz pisze ciekawie.
I don't really know how many such adverbs there are. At this point only one comes to mind: miło/mile (ł+ie merges into 'le').
Although the meaning is the same, there are instances where you can use one form, but can't used the other. For example: Bardzo mi miło and on jest mile widziany.