Some of my favourite Book Omens fics:
A Memorable Fancy by Argyle
Some Romantics have all the luck. (London, 1777).
(Aziraphale meets and inspires William Blake)
Come Live in the Country (With Me, My Darling) by KannaOphelia
After their conversation was interrupted by Death, Crowley and Aziraphale's minds were wiped of certain salient events from the last eleven years. But shadows remain. And Crowley is possessed by the conviction that the bookshop is a very dangerous place for the angel to be, and some worrying nightmares about fire.
(Crowley convinces Aziraphale to move to the country with him)
From Soho With Love by ImprobableDreams900
Five ways Crowley thinks heâs like James Bond, and one way he doesnât.
(Really neat character study of Crowley)
Half-baked Temptations and Holy Ground by NotASpaceAlien
Aziraphale and Crowley cover for each other at the very beginning of the Arrangement.
Mirror, Mirror by ImprobableDreams900
Adam, Eve, and Crawly flee Eden through the Western Gate, and it turns out that that simple decision makes all the difference in the world...
(Crowley changes places with an evil alternate universe version of himself)
There Was a Tree in the Plaza by food_forever_Friend
Jamie Hernez sits in in front of his beloved tree. It's weak and sad and depressing. But⌠it wasn't yesterday⌠was it? Maybe, with a little hard work, he can make things better.
(Post-Canon fic about the guy from the scene about the new rain forests growing which is really, really good)