I have a combination of processes:
1. User must fill out a form with their name and email in order to get the download link. For this I use Madmimi.com.
2. I have setup a drip campaign. Basically what happens is that once my users confirm their email, Madmimi automatically sends out and email with an welcome text and the download links (the benefit here is obvious: I have the users email and I now have statistics about click rates on the link)
3. This drip campaign has two additional emails. One in 15 days and another in 30 days (after the signup).
The 15 days after sign up email, basically ask how's everything is doing and contains a link to a quick survey about the whole experience so far (I use Wufoo). Is a guided survey with close question.
The 30 days after sign up email is an open question about how they feel with the app. What does it mean to them, etc.
Also, my app sends me a log every-time the user uses it for the first time (here is where I haven't been able to do a full integration)
What I do is: I receive this log that contain the users email and some data about the usage. At that moment I fire up my email client and write a welcome email. This is a personal email from me to my user. I thank them, give them all my contact info and basically say: I'm here for you 24/7 (to this day no user has ever waited more than two hours to hear from me when they write) and I keep that promise.
Most of the time, the emails I get are basically about the same and my answers are very much alike.
To manage this and to be able to give it a personal touch, I installed TextExpander on my Mac and have setup several templates that contain most of my answers but not the full answer. This forces me to read what I'm writing and actually personalize it a bit.
This method, while not perfect has brought incredible benefits for my startup:
One client was having some issues with the app and my response was fo fast and so helpful that he could not believe it. Turned out the guy was a radio dj and had a show about entrepreneurship. We did a two hour radio interview.
Another client is actively pushing my app to his clients because of the customer support I gave him the first days he used the app. He was having some issues (all created by him) and I dedicated 6 hours to help this client. He is now one of my most active evangelist.
It pays, big time, to do customer support with passion. Let your users feel it and they will reward you for it.