WSPBuilder makes the process of building WSP files extremely simple as illustrated in a previous post. WSPBuilder supports many features including deploying files to the 12 hive as well as deploying assemblies to the GAC or the web application’s bin
Intro to WSPBuilder
WSPBuilder is a tool for building web solution (WSP) files to deploy out to a SharePoint farm. It is free, open source, and available on CodePlex here: http://www.codeplex.com/wspbuilder. It is a tool that, in my opinion, every SharePoint developer should