SQL Server express has now a light weight version which is called as Local DB.This is mainly intended for Developer and does not require any management.

Super easy to install and no management sounds a great offer for our developers!

The installer is 33 MB MSI package and as per Express teams confirmation you can get the first feel of Local DB in just 30 seconds!

It offers the same T-SQL language, programming surface and client-side providers as the regular SQL Server Express.

More details at

http://msdn.microsoft.com/en-us/library/hh510202%28v=sql.110%29.aspx

http://blogs.msdn.com/b/sqlexpress/archive/2011/11/28/simple-installer-for-localdb-has-shipped.aspx

Thanks for reading.