Thanks everybody for the help.
One of the reasons I ask is that many of Aikido's traditional pins (at least the ones I know) don't seem to be very robust. I certainly have been pinned effectively by experienced aikidoka, but I notice that most pins take a large amount of skill, practice, ki extension, etc. to execute well. I know there isn't a "foolproof" pin and that practice is important. It's just hard to imagine somebody (less than a shihan) really controlling an attacker in and ikkyo pin with his tegatana.
I'm just curious if there are any more practical pins that are consistent with the ethics of Aikido. What would you use to restrain an attacker on the street?