Clojure on Heroku with Noir and Mongo in 10 minutes (here via @Baranosky). This example uses a MongoDB instance hosted on heroku and shows how to hook that up to your Clojure code. 10 minutes from scratch to deployed webapp - not too shabby.
Analyzing Stack Overflow data using Clojure (here via @maclausen). Shows how to use Clojure to analyze the 5.9 GB XML datadump from Stack Overflow. A wc -l posts.xml on the file takes approximately 3 minutes, but Clojure handles it like a charm.