Searchdropbox is a project mainly written in JAVASCRIPT and RUBY, it's free.
Full Text Search with Dropbox
Allows you to full text index documents stored in your dropbox account. Upon authenticating, you can input the Dropbox directories to index.
Requires Solr 3.1.0 or above
Install Solr and run using the example configuration: cd apache-solr-3.1.0/example nohup java -jar start &
NOTE: You will want to configure Solr to only bind to localhost instead of all IP's which it does by default. In addition you will want to block all traffic to the default port 8983. Without these steps, solr will be unsecure and available for anyone to search your files.
Download and extract searchdropbox cd searchdropbox/config Update config settings with Dropbox application API keys in config.yml.example and copy to config.yml
To start and stop the application: thin -C thin.yml start thin -C thin.yml stop
Should default to running at http://yourhost:4567/
Uses sinatra, haml, ujs, dropbox, rsolr, and backbone.js.