Okay, ever since reading Cold Days, I've thought that Harry really needs to meet the Nac Mac Feegle. Fortunately, someone else thought the same:
The Cheese Stands Alone by shadydave: In which Harry Dresden, Winter Knight, must deal with a force that defeated the Winter Queen and gave Jenny Greenteeth a real headache. Also, demon cows and Lancre blue cheese. Pure, irresistable fun.