my bookshelf is full of them, I only own one 40k book that is exclusively Space Marine and that is Iron Snakes by Dan Abnett
Yeah...are you joking? There are tons of books that don't involve Astartes. I'd suggest the Ciaphas Cain series. Some people like Abnett's Gaunts Ghosts. There quite a bit more as well.
Rogue Trader books, Ravenor Series, Eisenhorn Series, a plethora of IG books.....
why is there a white guardsman helmet floating next to the chaos marine ? still looks good :)