Those interested in icebreaking vessels may find the following WINMOS Activity 2.1 final report, published in June, somewhat interesting:
A database of existing icebreakers in the world
While the emphasis is on the Baltic Sea, it gives a good overview on the worldwide fleet as well as different types of icebreakers currently in service. There are also some performance comparisons, although level icebreaking performance alone does not tell everything about the full operational performance of each vessel.