TopicalNet's software allows Internet businesses to classify content by page and place such pages into "topics" to better target information to Web visitors. I/Pro's Web analytics product measures surfers' activity and demographics across sites. TopicalNet, based in Woburn, Mass., plans to merge the relevant capabilities of both products to create highly detailed activity reports on Web surfers, while maintaining their anonymity. Through the acquisition, TopicalNet also purchased I/Pro's auditing software, I/Audit, which independently verifies Web site activity and traffic. Engage is majority-owned by CMGI.