luk bro,, its as simple as this...
u may connect any number of seven segment led's to only one port of microcontroller..
but it may use addition number of pins of ur controller
i.e.
if u want to use four seven segment display then in addition with the seven pins of a single port,, u require four different pins....for switching operations..
1.just connect the power and ground of each of the seven segment led via transistor or a switch...
2.short the data lines of all the seven segment and finallly take out seven wires only...
3. now u r having 7+4 wires...
4.connect the seven wires to any of the port and make the adjustment for the other four also..
Now, it is just a simple program that enables you to show your data on seven segment led....
if you are interested-- the concept is of time division multiplexing on the seven segment led
(the 7 segment led switches with a very high speed, machine cycle of your controller) so you are able to see different data on the 7segment leds..