Creating centralized DBA database
On SQL Server 2008 R2 I'd guide you to SQL Server Utility Control Point, with some details here.

From MSDN description:
"The SQL Server Utility models an organization’s SQL Server-related entities in a unified view. Utility Explorer and SQL Server Utility viewpoints in (SSMS) provide administrators a holistic view of resource health through an instance of SQL Server that serves as a utility control point (UCP). Entities that can be viewed in the SQL Server UCP include:

Instances of SQL Server
Data-tier applications
Database files
Storage volumes


Resource utilization dimensions that can be viewed in the SQL Server UCP include:

CPU utilization
Storage space utilization"


On 2008 and earlier - MOM, as Gaius pointed, or maybe give a try to Multi Server Administration as defined by MS. You can see detailed article on SQLServerCentral Multi-Server Administration or on MSDN.