I'm developing an mp3 player where I have a PlaybackProxy wich handles sound playback, volume, id3 etc but I do not know what the data for this proxy should be.
Can anyone suggest an aproach to this!

While browsing the demos and the forum I realized many people use RemoteObject for remoting and i wanted to point a very nice AS3 remoting library called SSR (Super Simple Remoting). Features like caching and paging makes it a great alternative to RemoteObject!
Links :
http://www.osflash.org/projects/ssr/
http://blog.rubyamf.org/?p=103
Also regarding Rails remoting there is a plugin named RubyAMF that I think is better than WebOrb for Rails
because it doesn't require configuration files and it's faster.
These two should definitely be checked out!
Please post your opinion!