The Energon Pub

By this I mean any Seeker toys that are not Starscream, Thundercracker or Skywarp, nor any of the Coneheads. Or the Rainmakers or Sunstorm.

I like Seekers, but there doesn't appear to be a great variety of the toys even though they appear to be among the most numerous of the Decepticon 'subspecies.'

Are there any toys that are just the 'generic' Seekers? Or at least aren't given names?

What?

Any toy that Hasbro makes or Takara makes always has a name. There have been a few exceptions to that, most notably during Beast Machines.

Hasbor Produced Drone figures to match with the cartoon. Tank Drones and Motorcycle Drones. Nameless, lifeless drones controlled by their respective commanders, Tankor and Thrust.
Mysteriously no AeroDrones for Jetstorm, which would have made a good seeker army builder.

But as far as I know Hasbro has never produced a random seeker and not given it a name of a pre-existing one.

OTFCC 2003 featured a set of Heroes of Cybertron Seekers which included three "Air Warrior" generic purple figures:

http://tfwiki.net/wiki/Air_Warrior#Heroes_of_Cybertron

Here's an entire article dedicated to seekers. I don't know if this qualifies as 'Non Canon,' but there were a number of no-names and filler seekers used throughout the history of the Transformers. A generic purple "Air Warrior" was released as a set of 3 in a 'Heroes of Cybertron' six-pack exclusive available at what I believe was the last year of OTFCC.

http://tfwiki.net/wiki/Seeker

No variety in Seekers? If we include all the ones in your list (that actually have toys) we have 8! And we're not even going into the different types of Starscreams there have been.

Moreover, if Hasbro or Takara made a new Seeker it'd immediately become canon.