You probably looking for some free scripts? Just be careful because larger sites might not want to trade with you because they know you'll have a traffic leak due to the script skimming 2-5% of your traffic.
http://www.scriptpulse.com/ - TradePulse
http://www.arrowtrader.com/ - Arrow Trader Core
http://www.cjoverkill.com/ - CJ Overkill
http://www.tradeexpert.net/ - Trade Expert
http://www.smarttraffictrader.com/ - STT
http://www.slothtrader.com/ - Sloth Trader
http://www.adultwebmasterinfo.com/ucj/- UCJ
That list should get you off the ground...