Widget Manager is a free Mac OS X preference pane developed in 2005 to organize, install and remove Dashboard Widgets (a major new feature in OS X 10.4!). The initial release of 10.4 had no way to remove Widgets once they were installed, or to modify the default set provided by Apple. Widget Manager was the first and most popular app to fill this niche.
I have no plans to continue active development, and it's been a number of years since the last release. However, pull requests are welcome if you still use Dashboard and want to help with maintenance!
Contact me @mbcharbonneau on Twitter if you have questions.