My chain slackens, rhythmically, while pedaling. While I know that these types of questions draw the ire of the gallery, I searched for this specific problem and came up short.

While pedaling my chain slacken on a specific area of the chain, and I've got that thing "tight". When the chain hit's the tight section it's pretty damn tight.

I'm thinking that it could be a chain-ring issue, or worse, a crank problem.

Any suggestions?

It's a common issue. There's nothing wrong with having slack as long it's not enough to allow your chain to derail. Sheldon Brown has an article on the topic

Chain ring roundness, bottom bracket shell alignment, bottom bracket spindle and cog roundness all effect the tightening and slacking of the chain.

You can throw money at it and buy a rounder chain ring, a rounder cog, a more precise spindle and a more precise frame.

Without spending money, and instead getting the most out of what you have, you can research Sheldon Brown's method of centering the chain ring.

Centering the chain ring will make things better, but it won't cure all of the cyclic tightening and slacking.

And spending money won't get you perfection, either: it will only get you closer to perfection.

Alrighty then. Thanks for alleviating my fears.

I would be more concerned with this. Your chain should not be too tight.