Topography:
万葉集の風景 (Scenery of the Man'yōshū) 
:
A collection of images of the locations and landscape references made in the Man'yōshū
Language:
Kanji Haitani's Man'yōshū Best 100 - 万葉集ベスト１００":
In-depth linguistic breakdowns of the poetry of the Man'yōshū, accompanied with their modern Japanese and English translations and notes on the historical context
The Japanese Text Initiative's Man'yōshū:
Made available here are daishi 'prefaces' to the poems, their original text in man'yōgana, their Japanese pronunciation, and their spelled-out pronunciation in kana
1000 Poems from the Man'yōshū:
The Nippon Gakujutsu Shinkokai translation of a selection of 1000 poems
Classical Japanese: A Grammar:
A comprehensive Classical Japanese grammar that was especially helpful in the translation of language used during the Nara period and earlier