Any way to get high-low values more frequent than every 24 hours from say the Bitstamp API ticker? The link only tells you how to get the value for every 24 hours.
This also seems to be a problem with every other exchange I've tried.
These functions return the high or low over for the past 24 hours. You can poll the API for this data as often as the API allows for (600 times over 10 mins according to your link). The data that it returns does only consider the past 24 hour prices however. If you want to find out the high and lower prices over a longer time frame you will need to look at historical ticker data and determine the high and low values returned from the data set that you are requesting.
Have a look at bitcoincharts for historical BTC data