Chrissy LeMaire shares some great community-driven Powershell modules:
dbops
dbops was created by Kirill Kravtsov.
dbops is a Powershell module that provides Continuous Integration/Continuous Deployment capabilities for SQL database deployments.
It is based on DbUp, which is DbUp is an open source .NET library that helps you to deploy changes to SQL Server databases. dbops currently supports both SQL Server and Oracle.
Read on for links to several more projects.