You can download Visual studio extension to manage Sql Server Compact 4.0 databases from visual studio from here :
http://visualstudiogallery.msdn.microsoft.com/0e313dfd-be80-4afb-b5e9-6e74d369f7a1/
If you want standalone Sql Server Compact 4.0 database management, you can download from here (SQL Server Compact/SQLite Toolbox):
http://sqlcetoolbox.codeplex.com/
http://visualstudiogallery.msdn.microsoft.com/0e313dfd-be80-4afb-b5e9-6e74d369f7a1/
If you want standalone Sql Server Compact 4.0 database management, you can download from here (SQL Server Compact/SQLite Toolbox):
http://sqlcetoolbox.codeplex.com/
