I use FBreader almost exclusively on my iLiad. Love it.
Regarding dotReader, the first link in my sig goes to a thread with a paper I wrote about using the kinds of facilities offered by dotReader to foster online reading communities. I discuss both the strengths and limitations of the existing version of dotReader. It's not a good choice for dedicated ebook readers because of its dependency on Firefox, but I'd love to see something like it for the iLiad and other ebook readers in the future-- particularly those with built-in network capabilities.