Application Pool Manager (Free) at Harbar.net. Systematically recycles your application pools through a GUI.
SharePoint Manager 2007/2010 (Free) at CodePlex.com. A free tool that shows details of your entire MOSS farm.
WSPBuilder (Free) at
CodePlex.com: A Free tool which allows a developer to package features into a .WSP that can be deployed quickly and without the fuss of modifying .XML or .DDF files. Has a Visual Studio plug-in or a command-line package.