Rebecca Mackinnon writes about the uselessness of sanctioning North Korea without the support of other countries. Matthew Yglesias agrees.
I feel that more pressure should be put on the European countries and our allies in regards to presenting an united front towards repressive regimes. Similarly, there should be more stringent enforcement of penalties against American companies that deal with embargoed countries.
That said, I am not sure that economic sanctions against North Korea could work. I am not sure how one would stop Chinese trade with North Korea without making massive concessions elsewhere (i.e. Taiwan).