iStat pro 3.0 is the next incarnation of the chart topping system monitoring widget
The Darwine project intends to port and develop WINE as well as other supporting tools that will allow Darwin and Mac OS X users to run Windows Applications, and to provide a Win32 API compatibility at application source code level.
Tutorial on the mac os x binary format
RCDefaultApp is a Mac OS X 10.2 or higher preference pane that allows a user to set the default application used for various URL schemes, file extensions, file types, and MIME types.