I recall seeing at least one way to get more AoO beyond raising your dex score. Anyone know what it was?
Raising your dexterity does not increase the number of attacks of opportunity you get each round. Each character has only one attack of opportunity a round unless they have some special ability which grants more.
Having a high dexterity and possessing the feat Combat Reflexes enables you to make extra attacks of opportunity. It enables you to make a number of attacks of opporunity equal to your dex modifier + 1. So, with a dex of 12 and combat reflexes you would have two attacks of opportunity per round.