Reporting Services's Ordered Numbers
A report I recently created required the use of a recurring number in a subreport in reporting services. Didn't know offhand how to do that, but figured it was easy to do. Along came RowNumber: http://msdn.microsoft.com/en-us/library/ms159225.aspx. This method takes a scope value which is a relative value to determine whether to continue incrementing numbers for the current scope, or to start back at the initial value.
In a subreport, providing RowNumber(Nothing) creates numbers starting at 1 up to X number of rows and starts over every time the subreport was created, the right action for what I was looking to do.