This app works just fine on my local computer. After pushing it to Heroku, static pages appear to be working but the blog section throws an Internal Server Error. I pulled the logs by running "heroku logs" and this is what I get:
==> production.log <==
/usr/ruby1.8.7/lib/ruby/gems/1.8/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `run'
/home/slugs/215194_e5b887e_c999/mnt/.bundle/gems/gems/thin-1.2.7/lib/thin/backends/base.rb:57:in `start'
/home/slugs/215194_e5b887e_c999/mnt/.bundle/gems/gems/thin-1.2.7/lib/thin/server.rb:156:in `start'
/home/slugs/215194_e5b887e_c999/mnt/.bundle/gems/gems/thin-1.2.7/lib/thin/controllers/controller.rb:80:in `start'
/home/slugs/215194_e5b887e_c999/mnt/.bundle/gems/gems/thin-1.2.7/lib/thin/runner.rb:177:in `send'
/home/slugs/215194_e5b887e_c999/mnt/.bundle/gems/gems/thin-1.2.7/lib/thin/runner.rb:177:in `run_command'
/home/slugs/215194_e5b887e_c999/mnt/.bundle/gems/gems/thin-1.2.7/lib/thin/runner.rb:143:in `run!'
/home/slugs/215194_e5b887e_c999/mnt/.bundle/gems/gems/thin-1.2.7/bin/thin:6
Something wrong with the eventmachine gem, I suppose....but it works fine on my machine. So I'm not sure what's going on or how to debug it.
From your error log, it looks like you are somehow trying to access a database with SQLite3. Heroku's uses Postgresql though, so clearly your database will fail to open. Heroku generates automatically the database.yml file, so the error is can't be there but maybe you are requiring and using sqlite3 directly?