One of the recommendations I often give for SharePoint content databases is to create several of them right from the get-go. This provides partitioning to keep the databases at a reasonable size (you should keep them under 50GB). If you are approaching the limit, you can always create a new database. But what about splitting already existing databases into several smaller ones?

Here's a tool on GotDotNet that helps with this process. The tool "write locks, backups and restores Site Collections in a given input file to a new SharePoint Content Database." 

Does anyone have feedback on this tool or seen any other solutions?