They just collect themselves; I don't have much to do with it.
I have my first reader (Sony PRS-505) although with the depleted battery life and non-wifi, I don't use it as much. At the moment it is on my kitchen counter waiting for both new books and a new charge. Normally I keep it in my work tote and I read on it during lunch. Lately I have been using my iPad for lunch reading, but once I get new books loaded onto it, I'll switch back.
My second reader was a Kindle (keyboard, wi-fi only) that my husband bought for me on some special deal. It is full of freebies and copies of books that I have purchased for my son's Kindle. I keep it at home; it doesn't travel.
My third reader was a Sony PRS-T1, on clearance, to replace my PRS-505. (I say I bought it because my 505 was dying, but really I wanted to have wi-fi.) I keep this one at home as well; actually, I alternate reading one of my purchased books on this reader with reading a free book on my Kindle. These are also the two that I read the most books on and the most often.
My fourth reader is a NOOK HD+ tablet, also on clearance. I wanted the smaller size to carry around and use for reading (instead of my phone) but the store was completely out -- this was the only tablet they had left. At $99, it seemed like a good bargain, so I bought it anyway. It turns out that it is not the same size as my (full-size) iPad and I like reading on it better. I don't take it everywhere; I only bring it along when I know I'm going to be able to read on it for awhile.
I read on my phone, too, but only when I don't have some other reader with me. (Not very often; I'm pretty good at predicting when I need to bring the NOOK wit me.)