I like your article and believe that every table should have a primary key and that it won't hurt every table if it has a clustered index. Almost all our tables have primary keys (although some of that was forced upon us since you can't set up transactional replication on a table without a primary key.) Many of our tables have clustered indexes and we keep adding them to tables that don't have them. They help a lot to speed up slow running queries.

We use identity columns a lot as primary keys and they seem to work fine. One of the people I learned from said that joins are faster using int columns then with varchar and since we do a lot of joins on tables with a one to many relationship this seems to be fine.

Robert Marda