There is this site, goodanime.net, which I keep an eye on for new anime episodes and annoyingly doesn't provide an RSS stream. So I made this little ruby app, using nokogiri to parse their HTML front page and sinatra to serve the RSS, then deployed it to Heroku.
There is very little code, it's just HTML parsing, there is no persistence (I let the RSS client do that). Not a very interesting app unless you have the same kind of need, or if you just want a sinatra setup with guard-minitest / travis-ci.