I'd just like to give a shout out to a great product I've been using recently called VistaDB (nothing to do with the windows OS!).It's a .net managed database - what this means is that you can host databases in medium trust environments (eg, a shared webhost, such as Fasthosts), and deployment is a snip (xcopy your app / website, the vistadb dll and the db file). It shares datatypes with Sql server, and is a breeze to use.It's not competition for sql server, it has different goals (mainly to be a managed database), but it makes it seriously easy to develop a commercial product that can be deployed simply by file copy.I'm currently investigating microsoft's Entity Framework (currently only compatible with sql server), although, unlike LINQ to SQL (which will only ever be compatible with ms sql), the Entity Framework has a provider model, allowing it to target different databases. When the guys at vistadb create their own provider (which is on their roadmap), the combination should be awesome.I'm planning on writing an article or two on Entity Framework soon.[tags]vistadb, entity framewor, linq, sql server[/tags]