Apparently the cookiebombs were a result of an LJ glitch. They were marked as free on the virtual gift page, so naturally people had fun with the largess before LJ realized they had a problem and fixed it. Too much to hope that free virtual snowflake cookies might have been part of LJ's Christmas spirit, obviously.
I was beginning to wonder if I'd somehow missed membership in a secret LJ cookie gifting community, so I was pleased to find out I hadn't, because I would have enjoyed being a member of that. :)
Free or not, I'm still really touched that so many people who were giving cookies thought of me. Thank you so much, everyone. :D