Microsoft has recently released an update to the Central Administration site that makes it easy to move a Site Collection between different Content Databases. The Batch Site Manager can be very handy if you need to break up your content across multiple Content Databases – possibly sitting on different SQL Servers. The same tool also allows you to lock and delete site collections:
http://technet.microsoft.com/en-us/library/cc508852(TechNet.10).aspx
