A gem for your rails project that suggests indices for you to add in your database. It looks for unindexed foreign keys, and what columns actually get queried.
Add this line to your application's Gemfile:
And then execute:
bundle exec rake suggest_db_indices
0.1.0 (July 8, 2012) - Added the rake task.
0.0.3 (July 4, 2012) - Added justification for each index added, made log file handling more robust