I'm from the CMH area. There is one based at TZR (Bolton) called "CMH Aviation" that used to operate 3 B100's. They are in a bad way and only one B100 is flying due to what I am told are maintenance issues (engine TBO) and one was lost when an owner died of natural causes. They've also got a Citation II that's a leaseback but it doesn't fly much if at all on any given week. A very liberal estimate of 2 trips a month would be pretty close.
Million Air has a few airplanes (or at least had) at CMH. Netjets is at CMH. Airnet/Jetride is at Rickenbacker. I saw a job posting for a lear 60 operator called "Star Jets" but had no idea who/what/where/when/why they were. I sent an email and had no reply just to learn who they are, where they're based and the like. One theory could be it's a play on Airnet's "star check" but I'm skeptical of that.
Not real up to snuff at OSU...I never really need to go there.
LHQ (Lancaster, OH...SE of CMH) has a Cheyenne on a 135 ticket.