user10931: I work in a robot using arduino, and i have a few questions:
It is possible to increase the speed of a servo, for example a parallax?
It is possible to measure the current that pass through a servo?

user7282: Part 1: Can I increase the speed of the servo motor?
Solution #1 :
You can run your servo motor at its maximum rated voltage, which will give you the fastest response. If angle is all you want, that should be ok. 
Solution #2 :
If speed control is just as important, you're better off using a DC motor with an encoder. You will have to write a PI control loop, but in return you will be granted a fine-tune control and potentially superior performance.
Solution #3 :
If you need to hold a physical load accurately at a certain angle, then I would go for a stepper motor. But you need to make sure that you do not overload it, as it will cause a misstep. 
Part 2: Can I measure the current?
The simplest and cheapest method, is to connect a current sensing resistor to your servo and measure the potential difference using the analog input. Since the resistance is known, you can calculate the current using the formula I = V/R.
Two things to make sure: 
1) Your resistor power rating is not exceeded.
2) The voltage difference has to be large enough to be measurable. (e.g. 2 ohm resistor gives .05V @ 100mA, .5V @ 1A and your Arduino analog input may have the resolution of roughly 0.005V)
What? Did I hear you say that the accuracy isn't good enough? Well actually you can buy an op amp to amplify to the scale that you need. Or to make life easier: buy one from Adafruit. :p 
Hope this helps.

10931: <p>I work in a robot using arduino, and i have a few questions:
It is possible to increase the speed of a servo, for example a parallax?
It is possible to measure the current that pass through a servo?</p>
 7282: <h1>Part 1: Can I increase the speed of the servo motor?</h1>

<h2>Solution #1 :</h2>

<p>You can run your servo motor at its maximum rated voltage, which will give you the fastest response. If angle is all you want, that should be ok. </p>

<h2>Solution #2 :</h2>

<p>If speed control is just as important, you're better off using a <a href="https://www.parallax.com/product/28819" rel="nofollow">DC motor with an encoder</a>. You will have to write a PI control loop, but in return you will be granted a fine-tune control and potentially superior performance.</p>

<h2>Solution #3 :</h2>

<p>If you need to hold a physical load accurately at a certain angle, then I would go for a <a href="http://www.adafruit.com/products/324" rel="nofollow">stepper motor</a>. But you need to make sure that you do not overload it, as it will cause a misstep. </p>

<h1>Part 2: Can I measure the current?</h1>

<p>The simplest and cheapest method, is to connect a current sensing resistor to your servo and measure the potential difference using the analog input. Since the resistance is known, you can calculate the current using the formula I = V/R.</p>

<p>Two things to make sure: 
1) Your resistor power rating is not exceeded.
2) The voltage difference has to be large enough to be measurable. (e.g. 2 ohm resistor gives .05V @ 100mA, .5V @ 1A and your Arduino analog input may have the resolution of roughly 0.005V)</p>

<p>What? Did I hear you say that the accuracy isn't good enough? Well actually you can buy an op amp to amplify to the scale that you need. Or to make life easier: buy one from <a href="https://www.adafruit.com/products/904" rel="nofollow">Adafruit</a>. :p </p>

<p>Hope this helps.</p>
