Another feature that I can't live without in an editor is “Go to Definition”. Basically, if you are examining a variable or procedure and you want to get to the definition, just press a hotkey and the editor will position you at the definition. If the definition is in another file, the editor will open and load the file and position you at the right place. You can get back to the place you came from by pressing another hotkey.
This feature is reasonably common and is found in Visual Slickedit, VIM, the Visual Basic Application editors (Excel, Word and Access) and even the Visual Studio .Net IDE (although this took some digging to find). Again, I haven't found a way of doing this in BBEdit.