GIS Cluster Analysis

Hello Exchangeperts,

I was asked to write a function that identifies a cluster of latitude and longitude points from GPS tracks of animals.  Each point has a date/time stamp and LAT.LON.  The point is to identify a den, shelters, birthing ground, or anywhere the creature has hung out for some time relative to time in motion, or even the time the tracker was in place.  I started looking into 'cluster analysis' and found a couple dozen techniques/algorithms.  I'm wondering if anyone has done something like this and can point me to code examples.  Are there required inputs from the user like distance of possible cluster points to other points, percentage of candidate cluster points vs. overall number, proximity and time components.  Is there any normally accepted criteria for what constitutes a cluster vs. the general data and how is that figured.  When I looked at the data points on a GIS program it was like porn, I knew one when I saw one; but how do I do it programmatically?

I'd be using VB.net

Thanks for your thoughts