We did at least one other variation, but I can't remember for the life of me what it was.

Coming back to me now! One of the other armbar variations started with you in the mount. Grab the opponent's tricep and pull up (ex: your right to his left). Your other hand grabs his gi lapel (ex: your left hand to his right side lapel), and punches it down across his throat. The pressure from the pull-up on the arm and pushing the gi lapel across the throat is very uncomfortable - you can damn near get a tap from that alone!

You then slide your knee up under the shoulder of the opposite arm you have trapped. He will most likely be trying to roll in that direction (ie; away from the lapel choke), anyway. Trap the near side arm while still keeping hold of the other arm (tricep). Bring your leg over and finish the armbar.

Still don't remember the other one yet.
"In case you ever wondered what it's like to be knocked out, it's like waking up from a nightmare only to discover it wasn't a dream." -Forrest Griffin