Have you ever heard an album you'd call "doom rock?"

Not metal, not Sabbath.  This is the closest I can think of: Whatchimacallit by Brick Layer Cake.

I'd suggest that there are a few Danzig tracks that fall into that category as they have that doomy Black Sabbath atmosphere but still sit well within the confines of rock. A lot of those 70's inspired heavy psych & stoner rock bands like Witchcraft probably fall into that category too. In truth though, I've never felt the urge to label a release as doom rock. I tend to go one way or the other.

Doom rock is apparently a nickname for occult rock, and a few early bands of the genre such as Blue Oyster Cult and Coven are considered influential in developing heavy metal, doom metal, sludge metal, and stoner metal. I've heard a few songs by Uncle Acid & the Deadbeats, would they be considered doom rock, considering their slow tempo yet focused on rock more than metal in their recent material?

By definition stoner rock can include doom riffs. I see Uncle Acid & the Deadbeats as sitting in the stoner metal/rock & heavy psych space personally. Is doom rock essentially stoner rock without the psychedelics? I don’t think so. I think it’s very much an interchangeable term for the occult hard/progressive rock bands that Andi mentioned.

Doom is also about an atmosphere of dread, something rock can potentially create without metal guitars.  Stoner can have various atmospheres.  In fact, I would even say Songs for the Deaf has some noticeable punk rock and post-hardcore in it.

Black Widow's Sacrifice from 1970? Latterly, Blood Ceremony have quite a few tracks that would suit the descriptor I would suggest. There are probably loads of examples, slower songs that conjure an atmosphere of dread aren't restricted to metal by any means. Early-70's underground  heavy psych is almost certainly full of such tracks.

Black Widow's Sacrifice from 1970? Latterly, Blood Ceremony have quite a few tracks that would suit the descriptor I would suggest. There are probably loads of examples, slower songs that conjure an atmosphere of dread aren't restricted to metal by any means. Early-70's underground  heavy psych is almost certainly full of such tracks.

Now I'm getting eager to see what a RYM top 100 doom metal chart would look like.

I think some Deathrock falls into that category, I know Christian Death (at least the first three/four albums) tends to fit that description. Getting more into regular goth rock, but there's also The Danse Society, especially VI, and The Chameleons.

Lots of Slowcore. I find the less folky end of the genre to basically be Doom Rock. Wider Than the Sky by 40 Watt Sun is a great example, as are Low's first few albums. Codeine are this taken to the extreme, being incredibly heavy for a non-metal band. 

Dark/Depressive/Atmospheric Alternative Rock Albums like Alternative 4 by Anathema, or some mid-career Katatonia (Last Fair Deal Gone Down most of all) .

Some of the darker, more depressive Shoegaze bands creep into this territory occasionally (Nowehre by Ride, or My Bloody Valentine or Slowdive at their most depressive)