TTABlog® deals with trademark cases handled by the USPTO's Trademark Trial and Appeal Board and contains many lessons on trademark practice. Some of them can be valuable for anyone interested in trademarks. Another blog to consider is the Trademark Blog from the
Law Offices of Martin Schwimmer in Westchester, New York.
One of the significant cases mentioned on Martin Schwimmer's blog involves Adidas and Payless Shoes. Payless is facing a $305 million penalty for infringing the three-strip tennis shoe trademark of Adidas, one of the largest trademark awards ever. See comments at ConcurringOpinions.com/.