I've bought my Sony PRS 505 a year or two ago for a long train trip and love it. I use it exclusively for fanfiction (which is why I also ticked write ebooks). Because I prefer reading on the reader, every story over 10,000 words gets the epub treatment.

I've written my own little ruby script that creates the epubs from the .xhtml file (or from several files if the fic is very long).