i have an OLPC XO laptop, and I did successfully install FBReader on it a few days ago.
When I turn off the backlight and rely on the sunlight-readable black-and-white ebook display, I use either the ambient light in the room or an LED book light that I found out about on these forums, a Dual Flex music stand light from Mighty Bright.
I went on a download-athon on a few free sites, especially after installing FBReader which I prefer over the built-in PDF reader.
I haven't got a dedicated ebook device, but I after getting my feet wet with ebooks on the XO, I can easily see this becoming a regular habit for this avid reader of paper books.