In October 2007, Laura Williams of Safeco, Jim Marvin of FMC Technologies, and I gave a presesention on technology for corporate legal departments at the annual meeting of the Association of Corporate Counsel. One of the topics we covered was contract management. The material here (Contract Management Systems) includes contains a description of contract management software and an extensive list of vendors.
My list of vendors is now up to 36. Although that number is a bit overwhelming, this might be a good place to start for anyone researching contract management systems.