These novels are just for fun. All of them deal with Germanic myth in one way or another. I often disagree (sometimes vehemently!) with the authors’ views of Heathen culture and religion, but I was at least entertained by all of them. Fiction tends to be much easier to find than academic works, and reviews of novels are all over the Web, so this list is limited to authors, titles, and short descriptions.
Anderson, Poul. Hrolf Kraki's Saga. Novelization of the life of the semi-legendary hero Hrolf Kraki.
Anderson, Poul. War of the Gods. Based largely on Saxo Grammaticus, this novel recounts the life of the Norse hero Hadding.
Crichton, Michael. Eaters of the Dead. The first couple of chapters are taken from the (real) manuscript of Ibn Fadlan. The rest is Crichton's imaginative reinterpretation of Beowulf told in Ibn Fadlan's style. This novel was the basis for the film The Thirteenth Warrior.
Grundy, Stephan. Rhinegold and Attila’s Treasure. A two-novel sequence based on the Volsung myth cycle.
Harrison, Harry. The Hammer and the Cross; One King’s Way; and King and Emperor. An alternate-history series about Heathens who successfully organize to resist Christianity in medieval times.
Holt, Tom. Who’s Afraid of Beowulf? Comic fantasy about twelve Norse warriors who wake from an enchanted sleep in modern Britain. The more lore you’ve read, the funnier it is.
Paxson, Diana L. Brisingamen. Freyja's necklace surfaces in modern-day California.
Paxson, Diana L. The Wolf and the Raven; The Dragons of the Rhine; and The Lord of Horses. Together these constitute Paxson’s "Wodan’s Children" fantasy trilogy based on the Volsung myth cycle.