After consulting the official D&D 3.5 faq, I've discovered that special attacks with attacks of opportunity are indeed allowed, but I consider them too dangerous to game balance and general sanity not to house rule out.  The possibility of attacks of opportunity provoking attacks of opportunity is incredibly obnoxious in terms of battle resolution, and I already hate D&D 3.5 enough.<br/><br/>Resolving a single attack in as many as  8 die rolls (AoO, counter AoO, touch attack, trip/grapple check, trip/grapple defense, touch attack, trip/grapple check, trip/grapple defense), is inredibly obnoxious in offline play.  Online, it should be banned under the geneva convention.  Even oWOD, one of the least efficient systems ever designed, only used 4 die rolls per attack.  (And I bet I could resolve an attack in 10 die rolls if I used book of 9 swords abilities)