Exercises like that often fall under the category of hobbyist retrocomputing but the reality is... old systems refuse to die.
Maybe you have an old app still lurking around, running against Oracle7 and you can't upgrade the DB for some reason. Your modern apps all run against Oracle 12c, but it would sure be great if they could pull data out of that old database. Unfortunately OCI stopped supporting Oracle7 about 10 years ago. You might even have an old copy of Oracle 8i lying around. If it wasn't so expensive, you'd have chucked it for all the good it does you today.
Relay to the rescue!
In my experiment, I accessed Oracle7 from Fedora 20 via an instance of SQL Relay running on Redhat 6.2 (not RHEL, but old, pre-Fedora Redhat 6.2) using OCI from Oracle 8.1.7. Of course, I wouldn't recommend using Redhat 6.2 in production, but you could run a still-supported operating system like Solaris 8 or 9 x86 in a VM and get the same result.