When using a representation (with ~15 symbol rules) I get all symbols in the legend even though only a few are located in the layout extent. Not all maps need all of the defined symbology. How can I limit the representation sybols to those found in the layout extent? (dynamically and without having to convert sybols to graphics...)
This is a current enhancement that will be included at 10.1: [NIM003938 Provide option to constrain unique values renderer legend (and possibly classified renderer too) legend to data in current visible extent]. In 10.1 they are called Dynamic Legends. There are some unsupported ArcScripts (http://arcscripts.esri.com/details.asp?dbid=16097) that do similar things, but they don't appear to be updated for version 10. You may want to consider contacting the author of this script to see if there is a more recent version of the "legend limiter."