Feats

Combat Reflexes [General]

Benefit: You may make a number of additional attacks of opportunity equal to your Dexterity bonus.

With this feat, you may also make attacks of opportunity while flat-footed.

Normal: A character without this feat can make only one attack of opportunity per round and can't make attacks of opportunity while flat-footed.

Special: The Combat Reflexes feat does not allow a rogue to use her opportunist ability more than once per round.

A fighter may select Combat Reflexes as one of his fighter bonus feats.

A monk may select Combat Reflexes as a bonus feat at 2nd level.

Source: SRD 3.5 Feats