Amazing how discussion spreads.
Two offerings.
For circuit frequencies see the thread on this forum called, I think, Frequencies. Then try a search on frequency for the forum overall. Then try the
http://www.marshalspost.com/circuits.php for some circuit specific information (and don't forget to feed back new or corrected information). Then try Google. Lots of information (of variable quality/age) around.
When observing and the flag point is some way away (other side of the circuit or Lodge in for example) I give the flag marshal one of these personal radios and we can then discuss things quietly rather than making a spectacle of us shouting or employing arcane hand signals.
And, yes, I personally always have a scanner so as to be informed.
Regards
Jim