is it possible for allainces to communicate with the tube handlers on the other side of the field like different colored flashlights or scarfs ect. ect.?
Section 5.5.7 of the Rules:
5.5.7 Special Equipment Rules
<T25> The only equipment that may be brought on to the ARENA is the OPERATOR CONSOLE, reasonable decorative items, and special clothing and/or equipment required due to a disability. Other items, particularly those intended to provide a competitive advantage for the TEAM, are prohibited.
<T26> Devices used solely for the purpose of planning or tracking strategy of game play are allowed inside the ALLIANCE STATION, if they meet ALL of the following conditions:
Do not connect or attach to the OPERATOR CONSOLE
Do not connect or attach to the FIELD or ARENA
Do not connect or attach to another ALLIANCE member
Do not communicate with anything or anyone outside of the ARENA.
Do no include any form of enabled wireless electronic communication (e.g. radios, walkie-talkies, cell phones, Bluetooth communications, WiFi, etc.)
Do not in any way affect the outcome of a MATCH, other than by allowing TEAM members to plan or track strategy for the purposes of communication of that strategy to other ALLIANCE members.
Bringing scarfs and/or flashlights would violate <T25> if they “provide a competitive advantage for the TEAM”. Also, if any of the robots are using a light sensor during the match, then a flashlight could effect the outcome of the match.
As for the scarfs, if you could convince the refs/GDC that you were just tracking strategy and communicating the strategy to the alliance members on the other side of the field, then it could be ok.
I would just use hand signals, since there is nothing against that since the hands are part of your body.
Alternativly, one could have different colored lights (red, white, blue) actually on your robot. If clearly visable and it were explained prior to the match it would be fairly difficult for feeders to misunderstand what tube you want.
We have also been thinking of this, and some of our team does not think it is important to communicate with them. I feel as if a good communication system could win the game. If you know how to maximize your points, and you only have 30 seconds or so, the correct tube is vital to winning the match!
We have come up with a few ideas, but some are looked upon as useless.
For me I see it is vital instead for that human player, the feeder, to have a good grasp of knowing what tube to give by looking at the tubes already scored, where the uber-tubes are, and what tubes other robots from the alliance are currently carrying or picking up etc.
In case plans need to be changed perhaps you could make the robot do certain motions with the arm or drive-train to indicate what tube as it goes into the lane.
It appears that the robot must make the signal to me though there is always the chance the wrong signal is given.
The thing about the human players is that they do not always know what they are doing. Look at 2009 for example. Do you know how many penalties were assessed because people threw the empty cell over the wall instead of through the hole? 
You cannot really trust another teams human players. Its nice to think you can, but you want to make sure you have control of the whole situation.
I like the idea of a light on the robot, the only thing is that there will be a reaction and pickup time for the human player. The sooner he knows what game piece to put on the field, the faster the whole process goes. To me, that means once the robot picks up the game piece it will place on the pegs, the human player should be told what piece needs to be put on the field next so he can prepare for the next loading.