IDNcyclopedia - Provides insightful news and commentary for the IDN industry.

Exody - Exody is a huge resource of information for IDN pros. They have a subscription service for $35/month which features deleted domains, on-hold domain, and other tools. The IDN Research tool also provides similiar information, under the File -> Domain lists menu after you have purchased a license.

IDN Tools - IDN Tools is a free service that links out to the major IDN resources on the net. Lots of free tools to check for IDN domains. They provide an IDN sales history page, which shows a recent list of IDN domain sales over a $500 value.

Take More Risks! - Matt's blog is an interesting resource for online marketers. He blogs about his experiences with internet marketing (including the same of domains), monetizing adsense and affiliate programs.