The best replacement for servlets is jsp.

The best alternatives to servlets are rated as following:
★★★★★  jsp
★★★★  cgi
★★★  applets
★★  struts
★★  web services
★★  portlets
★  jsf
★  filters
★  facelets
  mod perl
  jsps

Your alternative for servlets is not listed? Suggest!
Speaking about servlets, one probably shouldn't forget about jsp examples.

Other search terms related to servlets and their ratings are:
★★★★★ jsp examples
★ applets
★ web.xml
You have in mind a companion for servlets and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of servlets in all years. Click on graph for more.
servlets
jsp
cgi