Hi... i'm looking for rgb dot matrix led... I need it for make a real-time display... someone know where can I buy it??? (a site that sends electronic components in italy and if possible in few pices)
and... how much difficult is to manage a dot matrix led with arduino and a light sensor?? how many matrixes can I connect??
thank you... above all for the patience...
alessia 
Here's one from Sparkfun. You can put serveral together.
Fun absolutely, until you see the 60$ pricetag
You can make one yourself for around $10 per 8x8 array.
Takes a lot of patience though.
There are two ways to drive them.
Either on/off with a 74HC595 chip. You will need 8 of them for a 8x8 array.
On, off and everything in between with a MAX7219 chip. You only need one per 8x8 array.
The 595 is brighter however.
Both chips can be daisy chained together so its simple to expand.