Basically either solder wires onto the line or get another shield with feed through connectors.
However driving a servo and other motors ( you don't need a motor shield for a servo ) from the 5V line is a bad idea because they take more current than this line can supply.
I'm only thinking about powering 2 servos and 2 wheel encoders with it! It should be find I hope.
I use little pieces of stripboard or solderable breadboard/protoboard with 0.1" pin header in it to split up the power rail into little ones (hey, I just so happen to sell a lot of board just like that and bigger ones too )
In that case, with that "shield", I think the only way you're going to get onto the 5v is by soldering wires to that shield (or the back of your uno >.> ). You can also solder little pieces of protoboard right onto the bottoms of a row of pin header - but probably just better off with a wire running to a scrap of PCB where you split it up.
This is something that annoys me about a lot of microcontroller development boards. They never give you enough Vcc or enough ground pins to connect all the stuff you want to - so great, their board is super tiny... but you need a rats nest of wire or another scrap of pcb to split the power and ground up to connect more than one thing to it, and all of a sudden it's not so tiny anymore, and it's ugly too.
I think you're right, I'm gonna solder one wire that will power a small pcb plate like you showed me. Or I might just use my breadboard.
I kinda agree with your point. I was suprised when I realized arduino has only one 5V pin.
By the way, what is the current max for the 5V pin? I can't get to find the same answer on the web. I'm powering the arduino throw the VPIN with 6V if that can help. I just want to be sure that my servos don't burn my arduino.
Thank you for your answers!