I wrote a handy function today that will return the server file system path of the acting Application.cfm file for a ColdFusion application. It works by working its way up the directory tree until it finds an Application.cfm file. If it doesn't find one it will throw an exception.
I gave a presentation at my local CFUG yesterday called 10 Underrated Functions in ColdFusion, I plan on doing one for tags as well at some point. Here was my list of functions, in no particular order:
ValueList - Returns the contents of an entire query column in a string list.