Who is Freyja?
As Urðavingi (Foundationalist) Asatru, I feel that the lore of literature, history, anthropology and science reveal the purest essence of who Freyja is, beyond any (even my own) personal experience with the goddess. Conflicts between personal experience and the lore arise quite often, and when increased numbers of personal experiences are at odds, the only thing linking them together is the lore. By that token, it can be argued that just as each persons own history is a recording of the truth behind who they are regardless of the personal opinions of others, so is Freyja (or any of the gods for that matter) also defined by Her history.
The goddess Freyja was worshipped amongst an entire pantheon of deities by central, northern and eastern Europeans (of Germanic and possibly Slavic language groups) from as early as the year 200 c.e. (of the common era) to as late as today. The religion originally had no agreed upon name unto itself, for it developed in a region of diverse tribes and peoples. Based on a modern movement in Iceland to reclaim its status as a world-religion, it has come to be known in America as Asatru (lit. "True to the Gods") or more simply 'Heathenry' (as opposed to Paganism which may be inspired from Celtic or Greek sources). Asatru as a whole is observing a global rebirth - even if it is a difficult one.
In Asatru, every God is beneficial and has a specific role in the universe to fulfill - just as every person in a community has a role. Freyja's role was that of divine Hostess and Inspirer of creation. In her role as Hostes she promotes marraige and the bonds of families into clans. She also soothes hostilities by showing respect to even those who would harm her (e.g., Hrungnir). As the divine Inspirer, she promotes imagination for Arts & Crafts, passion for building of all forms, and lust for procreation. Freyja was invoked to bring people together and resolve issues of passion and conflict - but the product of those efforts was overseen by other divine beings. One concept that She does NOT oversee is conception - which is the role of her brother Frey. Though Freyja has a daughter, the goddess Frigga was the divine Mother and the Household. Freyja is also the goddess of sorcery, which is actually difficult to define. Her own use of sorcery is not well represented in the lore - though it is clear that She uses those skills to fulfill Her role in the universe.
Freyja is a prominent figure in Viking literature. The world famous Eddas and Sagas abound with tales of their gods, including Her. She has Her place among the other gods of the pantheon, yet it is known that there were specific temples and cults dedicated to Her as an individual goddess (but still as part of the pantheon and not as a monotheist movement).
Records of cults dedicated to Her are sparse, but they are consistently indicative that a large percentage of the population worshipped Freyja, if not exclusively, as a distinctive figure in her own right to be singled out for some purpose. Most evidence left to us are large numbers of place names and family names that speak directly of Her worship. Place names like 'Fruvik' ('Freyja's Stream') and personal surnames like 'Fruehauf' ("Freyja's-Hof"/"Freyja's Temple") are common throughout all of the Germanic speaking countries.
Even so, actual record of cult practices are not easily found, if at all. Many presume (possibly accurately) that the places and activists of her cult worship were singled out by Christian missionaries for eradication. Their reasoning is that any male deity may be used to convert the locals by changing his name to Jesus or Christ (or a saint). A female deity, on the other hand, has no place in a Christian world, unless that female deity is compatible with the likes of Mary. Freyja is not compatible with Mary.
Most reconstructions of Freyja worship come from comparisons with other female deity worshipping cults in other religions. For instance, since so much of the lore refers to Freyja being a sexually active deity, she is compared with ritual prostitution within Greek and Sumerian cults. Having, supposedly, red hair and a fiery disposition she is associated with the Celtic goddess Brigit. One could also go as far as to compare her to Pele, the Volcano goddess of Hawaii, if one wanted.
The truth, however, is that what literary evidence we have was written down by Christian males asserting both their nightmares and pipe-dreams of a sexual female goddess with little knowledge of or regard for women.
What does appear in the lore is that a significant number of women worshipped her. Most likely a larger percentage of women than men, actually. This is important because what a woman looks for and gets from a female deity is something altogether quite different than what a man does.
Speaking as a man, understanding Freyja and understanding women in general is a parallel process. Being a man, women will project to me what I want to see in them. Unlike most men, I am unsatisfied with believing that what is projected to me is all there is. If I only got out of worshipping Freyja what I wanted from Her, then I wouldn't be honoring Her, but merely admiring Her.
So, the research of Freyja worship is far from anything useful. Certainly, one could map out place names and trace family surnames to identify regions and populations, but the specific practices of Her worship are probably forever lost to us.
On the other hand, we still have Her, and as long as we honor Her properly - our own inventions of worship should satisfy Her well.
Ma Freyja blotta.