This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
I don't think there is anything in the spec for doing this.
Check with the documentation for the container you're using to see what they offer. I know that Tomcat will show you the deployed servlets if you fire up the HTML Manager app and go to Server Status -> Complete Server Status you'll see a list of all the servlets deployed in each application along with some data for each of them.