You could do two people pointing guns at eachother and have the title be some random battle name.

First Ship Engineer?

The unknown engineer (and you could add a text like "here lies an engineer whose name is only known to him and unto his grinder")

Or "the lost expedtion" (text: to all those who went into the great black to never be sen again)

A random tombstone wich you can edit the text

and lastly the clasical captain going down with his ship (a guy in a command console and explosions all around him)

Some ships.
Eg-Red Ship
-Blue Ship

It'd be nice to have some sort of memorial to real life space missions, such as one to Sputnik, to the Apollo missions, Soyuz, ISS, Voyager, the shuttles.
Memorials to fictional ships would be cool to. (Yamato/Argus from Space Battleship Yamato/Star Blazers comes to mind, as well as the Macross)

EDIT: Nevermind the Yamato, as it left Eath in the year 2199 (at least in the japanese version) It would still be cool, though

My ideas:
Colossus of Rhodes style Engineer
Statue of Liberty style
Berlin triumphal column style
Greek athlete style (discos thrower etc)
Buddha style
Sitting lincoln style
Brasilian Jesus style

First Year of Space Engineers!

Possibly the whole crew of a large ship posing?

A GUMMY BEAR!
'and apon this spot rest a soul very missed.
Mr Gummy'

I think that a statue of a few engineers with guns, in a running pose, like they are part of an army, with the caption "In memory of those lost in space protecting our freedoms."

i think a engineer in a heroic pose with the ship below his foot could be a great statue

how about a group of engineers pointing assault rifles in different directions with a few dead engineers and one engineer in armor with a chain gun in his hand with a box of gattling rounds attatched. of course they'd have to be near something like a spaceship reckage to split the scene maybe one of the default fighters with the nose half buried from the easy start missions not sure what the caption should be maybe something like honor the fallen somewhere along those lines :D

Giant Space ♥♥♥♥....am I right?.................noo? Okay then...

Maek Rosa

probably way over the top and off topic the side statues of the hobbit the erebor gate dwarwes ^^ from left and right who are carved from out of the mountain side ^^ like this http://img3.wikia.nocookie.net/__cb20130318193218/lotr/images/b/b6/Erebor_gate.jpg or just staues like this http://farm9.staticflickr.com/8503/8384415171_1bd029b1d8_z.jpg