Ruby

Sensu-Admin is a nice GUI for the Sensu monitoring framework. However, installing it on Red Hat Enterprise Linux 6 ends in pain, since RHEL6 comes with an older version of ruby (1.8).

You might be creative and get most of the required gems installed but ultimately there will be gems that simply require ruby 1.9:

Microsoft Word 2011 lets you turn on the Track Changes feature and distribute your files to friends and colleagues. You can then see their comments and corrections.

Now consider the case of an editor of a scientific journal. The workflow goes something like this:

1. Receive article from fresh-faced graduate student.