Luke is a small desktop client for browsing Lucene indices. It is very useful for troubleshooting when you work with Lucene directly embedded in your application.
While upgrading an application from Lucene 3.4 to Lucene 4.3.1, I realized that Luke is not quite up-to-date with Lucene, it is stuck somewhere in 4.0.0 alpha.
But the good thing about Open Source is, if the original project owners lose time, resources or interest, others may show up and fork or continue the work.
A number of people have forked or copied Luke to GitHub. tarzanek/luke also offers binary builds on java.net, and this version works fine for me with Lucene 4.3.1 so far.