Statistical analysis of terrorist groups' longevity, aims, methods and successes reveal that groups are self-contradictory and self-sabotaging, generally ineffective; common stereotypes like terrorists being poor or ultra-skilled are false. Superficially appealing counter-examples are discussed and rejected. Data on motivations and the dissolution of terrorist groups are brought into play and the surprising conclusion reached: terrorism is a form of socialization or status-seeking.
http://www.gwern.net/Terrorism%20is%20not%20about%20Terror
This would, I think, fall afoul of Abrahm's point, '5) terrorist organizations generally carry out anonymous attacks, precluding target countries from making policy concessions;'. It's hard to be propagandistic if it's unclear what this deed is the propaganda of.
Hm. I'm far from an expert, and it could well be that there are ten times as many anonymous attacks, but off the top of my head I think of WTC '93, the Millenium plot, 9/11, London trains, Madrid trains, Israel suicide bombings, Munich massacre, Iraq beheadings, USS Cole, bombings of US embassies.
Not off the top of my head: Golden Mosque bombing, Tamil Tigers numerous bombings, IRA-related terrorism, etc. Scanning through this I find many more terrorist attacks that were done with a clear political or propaganda purpose.