tomcat : free ,choice it if you want a low charge solution,but tomcat isn't stable when doing heavy loads .
resin: costs $1000 for commercial license ,good choice if you only use jsp/servletorion: costs $1500 for commercial license,full j2ee support
resin: costs $1000 for commercial license ,good choice if you only use jsp/servletorion: costs $1500 for commercial license,full j2ee support
iPlanet Application Server costs $35,000 per CPU.