J.R.R Tolkien heavily relied on Norse and Celtic religion, when he wrote the Lord of the Rings, and The Silmarillion. Thus, at some level, they can be seen as the ancestors of modern fantasy literature.
Some revived the ancient religion, and consider themselves „Neopagan”. They can be considered as a minor (?) subculture.
There is a certain popularity for historical reenactment. Of course, in northern Europe, probably the most favored era for reenactors is the Viking age.
Influenced folk and rock music (with bands like Manowar, Therion etc.).
The day-names in English are named after norse gods. (Wednesday-Woden’s day, Thursday-Thor’s day, etc.)
We don’t know much about the exact „how” of norse religious practice. Supposedly, there were solitary keepers of faith in different settlements, isolated from each other.
Norse language was strongly speach oriented. Their rune-writing was most often carved in stone, so there aren’t much written sources left. The main sources are the works of Snorri Sturlson, an Icelandic historian, and the Gesta Danorum, by Saxo Grammaticus.
There are of course, sources of other nations, which the vikings contacted, but these sources are to be treated with care, as most were written by Christian figures, who had prejudice of pagan cultures.