Here is a Rack app that does a Google Search using Mechanize:
We are using Mechanize 0.8.5 and Hpricot 0.8.2. The most recent version Mechanize uses Nokogiri, which requires native libraries and therefore does not work on AppEngine. There is an effort to finish up the pure-Java Nokogiri, maybe YOU can help.
www.serabe.com/2009/12/31/helping-nokogiri-take-ii
Special thanks to _Why, Ola Bini and Nick Sieger for creating, porting and maintaining Hpricot. Mechanize is my favorite gem of all time, so thanks to Aaron Patterson and Mike Dalessio for creating such an awesome tool. Here is a nice screencast.
www.bestechvideos.com/2009/12/07/railscasts-191-mechanize
When using gems with Java extensions, appengine-tools drops the appropriate jars into WEB-INF/lib for you.
find .gems -name "*.jar" .gems/bundler_gems/jruby/1.8/gems/hpricot-0.8.2-java/lib/fast_xs.jar .gems/bundler_gems/jruby/1.8/gems/hpricot-0.8.2-java/lib/hpricot_scan.jar
"no such file to load -- appengine-apis/urlfetch from config.ru:3 "