If you are a NHibernate user and writing HQL queries like me, you definitely need to check out Ayende’s NHibernate Query Analyzer. With this tool, you can load up your NHibernate mapping files, your business model and a NHibernate configuration file, after which you can query the objects in the business model and see what sql is generated under water. It is also possible to execute the queries, so this tool is excellent for (performance) tuning your HQL queries.
Be sure to check out the flash demo, download the tool here.