As many as they decide I guess. Though I find myself laughing at myself rather frequently over how much tech I have. I have two laptops. One is going on five years old and a bit wonky, but still a good workhorse computer. The other is a very small lightweight (11" screen) machine that is just a step up from a netbook. It's great for travel and light work. I bought it because I was terrified that my workhorse would die in the middle of taking the bar exam. And buying it has meant that my workhorse has lasted longer.
In addition to the two laptops I have my Motorola Droid phone and a Kindle Paperwhite. My father had left me an iPad that was synced up to his Kindle account, but I found it cumbersome to use and not good for much besides reading (it was a 1st gen and most apps didn't work on it anymore). So I gave it to one of my sisters who likes to hack tech. Unfortunately this has left me with a bit of a problem. If I want to read my father's e-books on a Kindle rather than on a laptop (which is very cumbersome and not well suited for reading Kindle stuff comfortable IMO) I would have to de-register my Kindle and re-register it under his account (he made sure my brother and I had the account info), and then switch it back to read my stuff. Not a practical or workable solution. So after much thought and contemplation I decided to buy another Kindle (a simple Touch this time rather than another Paperwhite; doesn't have the built in light, but I can work around that). I also ordered a kick-ass cover
for it that reminds me a bit of Dad's tattoos.
While part of me feels kind of silly to have two of the same device, another part of me is thinking about how cool it is to have two entire libraries contained in such portable format.