Suhail, don't get me wrong, MixPanel looks awesome and I'm sure it will work for 99.9% of all startups out there, but we're just a little more neurotic about our stuff.
Here is one example that is hard for us to convert.
Monthly Active Users on a sliding scale. This requires 30 db writes every time someone signs on. Which we could do with 30 calls to mixpanel for every user sign on, but we decided to cache the user being counted in the user field and use memcache to batch the stat to one of our servers that will automatically write 30 different entries based on the key.
