I’ve generally been disappointed with the small response from the Hebraic community, in part because the Jewish tradition does in fact not only encourage but require prayer in numbers. Without a Minyan — essentially a quorum of Jewish males — there are all sorts of things you cannot do in Judaism. Here are two emails from the same guy:

Jonah,
I found this in “The Kuzari” (12th century defense of Judaism by Rabbi Judah Halevi — a fundamental text of Jewish literacy written in Socratic form):
The Rabbi: ………..a prayer, in order to be heard, must be recited for a multitude, or in a multitude, or for an individual who could take the place of a multitude. None such, however, is to be found in our age.
Al Khazari: Why is this? If every one read his prayers for himself, would not his soul be purer and his mind less abstracted?
The Rabbi: Common prayer has many advantages. In the first instance a community will never pray for a thing which is hurtful for the individual, whilst the latter sometimes prays for something to the disadvantage of other individuals [or to his disadvantage]. One of the conditions of prayer, craving to be heard, is that its object be profitable to the world, but not hurtful in any way. Another is that an individual rarely accomplishes his prayer without slips and errors. It has been laid down, therefore, that the individual recite the prayers of the community, and if possible in a community of not less than ten persons, so that one makes up for the forgetfulness or error of the other. In this way a complete prayer is gained, read with unalloyed devotion. Its blessing rests on everyone, each receiving his portion…………..A person who prays but for himself is like him who retires alone into his house, refusing to assist his fellow-citizens in the repair of their walls. His expenditure is as great as his risk. He, however, who joins the majority spends little, yet remains in safety, because one replaces the defects of the other. The city is in the best possible condition, all its inhabitants enjoying its prosperity with but little expenditure, which all share alike.
There is more, but this gives you the idea. I also found some other references to community prayer in a Kabbalisitc treatise on my shelf. In particular, it cites the plural in Psalm 102:18 (“He turned to the prayer of the destitute and spurned not their prayer”) and Deuteronomy 4:8 (“For what great nation is there that has a God so close at hand as is the Lord or God whenever we call upon him”) Although happily and proudly Jewish, I am very, very far removed from being a scholar of Judaism, so I suspect that the literature is replete with other examples dating at least (as I have found) from the middle ages, and supported by references to Torah. Finally, I recall (from some vague recess of my Jewish education) that it is said that if only every Jew on earth prayed sincerely on Yom Kippur (or perhaps on any given Sabbath, I don’t recall), then the Messiah would arrive. I hope this helps.

And…

Jonah,
Sorry to bother you again on this, but so far you haven’t posted anything from a Jewish point of view. Since my earlier e-mail (on Judah Halevi and the Kuzari), I have dug a little bit deeper, and it does seem that Jewish law prefers collective prayer to individual for the same reasons that Rabbi Halevi articulated. Of course Judaism does not discourage individual prayer (far from it, it would seem, based on the fact that several of the main biblical figures such as Abraham, Jacob and Jonah — among others I’m sure — pray individually). However, it appears that the tradition of a minyan derives from just this preference for collective vs. individual prayer.
Oh, and I mis-cited the Torah in my previous e-mail. I mentioned a quote from Deuteronomy 4:8 that is actually Deuterronomy 4:7. If you find my previous e-mail too long, off-message, incoherent or otherwise not fit for posting, please consider finding some way to address the Jewish perspective. Also, do you suppose that the Islamic practice of public calls to prayer five times a day suggests a preference for collective worship as well?