Timer In Capture mode.

Here's another one (Couldn't figure out the attachments option):

//******************************************************************************
//  MSP430F20xx Demo - Timer_A, Compare Mode, SMCLK
//  Give a 1 KHz square wave to P1.1 (pin 3)
//  Place breakpoint as inidicated below
//  Read the value in 'buffer' variable
//  buffer[i]-buffer[i-1] = pulse width
//  In this example Signal frequency = 1KHz, TA CLK = 1MHz
//  Captured clocks = 1M/1K = 1000
//  buffer = [1000, 2000, 3000, 4000....]
//******************************************************************************

#include <msp430x20x2.h>
unsigned int buffer[20];
unsigned char i=0;
void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  if (CALBC1_1MHZ ==0xFF || CALDCO_1MHZ == 0xFF)                                    
  { 
    while(1);                               // If calibration constants erased
                                            // do not load, trap CPU!!
  }
  BCSCTL1 = CALBC1_1MHZ;                    // Set DCO to 1MHz
  DCOCTL = CALDCO_1MHZ;
  P1SEL |= BIT1;                            // P1.1 CCI0A
  TACTL = TASSEL_2 + MC_2;                  // SMCLK, contmode
  TACCTL0 = CM_1+CCIS_0+SCS+CAP+CCIE;
  _BIS_SR(LPM0_bits + GIE);                 // Enter LPM0 w/ interrupt
}

// Timer A0 interrupt service routine
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A (void)
{
  buffer[i++] = TACCR0;
  if (i>10)
    __no_operation();                       // PLACE BREAKPOINT HERE
                                            // VIEW 'BUFFER' VARIABLE
 
}