Listed in the order I got them:
Kindle keyboard, Kobo Touch, Kindle Touch, Nexus 7, Kobo Mini.
I've included the Nexus as I do actually read on it more than I thought I would. My original Kindle was a 2i - the first one available in the UK. I sold that on ebay when I bought the K3 as I felt guilty because I didn't 'need' the new one. Then I got the Kobo but used one for home and one for travelling. Then... Well lately I've decided that if I call myself a collector then I can justify it to myself.