If it's for receive only, Stridsberg multicouplers are widely used by the scanner/monitoring crowd and work very well. They are available from ScannerMaster: http://www.scannermaster.com/Multicouplers_s/43.htm
The Electroline EDA-UG2402 and EDA-UG2802 are good alternative CATV amps that are much cheaper. Both are 0dB forward gain, which a good property for a CATV amp used for monitoring. The Stridsberg amps have the advantage of BNC connectors, while the Electroline amps have F connectors. We use Electorlines to feed old commercial radios off of a single antenna for remote monitoring and they work well for us. There's a sticky thread in the Antennas and Coax Forum on radioreference.com that has more information about multicouplers. If you search for Stridsberg, Electroline and multicouplers on the web, you'll get hits from hams doing similar things.
