Oblates are those individuals who have affiliated themselves with a monastery. These individuals are not monks, there are no monastic vows taken; they are laypeople, or clergy who have dedicated themselves to a special service, essentially.
The word oblate (from the Latin oblatus - someone who has been offered) has had various particular uses at different periods in the history of the Christian church.
The children vowed and given by their parents to the monastic life, in houses under the Rule of St. Benedict, were commonly known by this term during the century and a half after its writing, when the custom was in vogue, and the councils of the Church treated them as monks.
Oblates are individuals, either laypersons or clergy, normally living in general society, who, while not professed monks or nuns, have individually affiliated themselves with a monastic community of their choice. They make a formal, private promise (annually renewable or for life, depending on the monastery with which they are affiliated) to follow theRule of the Order in their private life as closely as their individual circumstances and prior commitments permit. Such oblates do not constitute a separate religious order as such, but are considered an extended part of the monastic community, and as such also often have the letters OblSB after their names on documents. (Wikipedia)
Oblates exist in every Christian denomination that has benedictine monasteries (typically, Orthodox, Catholic, Anglican, and Methodist).
The Orthodox Church has had oblates since the beginning of such things, as the original benedictine monasteries, though under Rome, were still part of the one Church (before the split). For a while, a benedictine monastery was maintained on Mount Athos (a mountain and peninsula in northern Greece that is famous for it's monasteries). until the 13th century.
After that it seemed that benedictine monasticism was lost to the East.
However, in the early 20th century, there was a movement to recover the lost Western Rites of the Orthodox Church, and in this movement brought back the benedictine monasteries - which of course brought back Orthodox oblates.
Oblates can be any one: male, female, married, celibate, clergy, layperson, some can even be of a different denomination if the monastery allows such.
But why be an oblate?
Well, for starters it can help to deepen your spiritual life because you pray the Hours (1st, 3rd, 6th, and 9th), as well as Orthros/Vespers. In addition you read from the Rule of Saint Benedict daily, as well as scripture. The Rule can help teach humility, patience, and the importance of hard work. You are reminded daily to pray for the monks, and they also pray for you (which, lets be honest, we could all use some one praying for us on a daily basis).
But it's not just prayer. You support the monastery. You can send them money for things they need, such as vestments, supplies, food, etc. You can also visit the monastery to help out around the monastery (fixing things, building things, planting things, etc.). You get the satisfaction of being able to help others.
Above all, you seek God in all things, and live your whole life for God.
If you are interested in becoming an oblate through this poorly written article then please check out this link which has more links to check out (also above those links is an article about the Rule of Saint Benedict).