Estonia doing well with "austerity" budgets, and Spain is not an example of "austerity"
There are a couple of things that Krugman leaves out of his discussion.
1) Estonia was getting worse relative to other countries when it followed more of a Keynesian policy and has been growing relative to other countries since then. Figure from The Global Post (click to make larger). As that publication wrote: "Still, its recovery, after implementing austerity, is intriguing." By the way, the publication also accuses Krugman of cherry picking data to show.
Note on Spanish "austerity." Spain is in a lot of trouble, but it isn't because of "austerity." From the WSJ.com.