Freyja Sightings

Beowulf 700 - 1000
Freyja may not be mentioned in Beowulf, but her beautiful necklace, Brisingamen, is. Check out necklace mention at line 1199.
Der Ring des Nibelungen (The Ring of Nibelung) 1848 - 1874
Richard Vagner's Der Ring des Nibelungen epic operas about Norse mythology feature a character named Freia, inspired by the goddess Freyja.
Erik the Viking 1989
Freyja pops ups in the cheesy '80s comedy Erik the Viking.
World of Warcraft 1994 - 2011
Freyja appears as a boss in the online role-playing game World of Warcraft.
"Freya" 2005
American heavy metal band The Sword wrote a song about Freyja called "Freya." In the song, Freyja is performing her role as a Valkyrie, selecting dead warriors to go to Valhalla. You can read the lyrics here.