Israel Steinmetz from BellaOnline (don't look at me like this - I normally don't read women mags) wrote a nice article (http://www.bellaonline.com/articles/art28527.asp) explaining why to read e-books on your PDA. Excerpt:
The key to the advantages of reading eBooks on a PDA is convenience. Reading eBooks on a PDA provides opportunities for reading that mesh with one's life. One can carry one's grocery list on the PDA, use it for shopping, then read a book while in the checkout line. (Reading the TV Guide or beauty magazine in line is no longer necessary.) Or, one can turn out the lights, get into bed, and read a book on a PDA (with the backlight on) until falling asleep. (No more falling asleep with the room lights on.) eBooks on PDA's are books that fit into our lives.

I agree... reading with a lit display at night works great, and doesn't require the lights to be on in the room. People have claimed that it is bad for the eyes, but I think I have less eye strain when I read on my PDA than with a paper book with small print. And with a PDA, I can enlarge the text on days when my eyes are tired. I'd say reading on a crt or laptop screen is harder on the eyes than reading on a PDA.

Every night I read my PDA to sleep with the whole backlight thing and text sizer thing and all. I love it, it's the best, except when I fall asleep and the Auto-Scroll doesn't and the next time I read the book I'm at the end. Then I have to go back to my last bookmark and flip forward until I'm back at the right spot. (I'm getting better, though.)

An article like this will never appeal to my GF, though, because I think the whole point of her going to the grocery store is to read the magazines in line. And until the come out with Chinese romance novels (in Chinese), she'll never read eBooks on her Zire71. (But if they did, then I'd never get her to stop. Those romance novels are worse than crack.)

POL9A

People have claimed that it is bad for the eyes...
With the correct adjustments in brightness and text size, I don't see how reading in a PDA could harm your eyes.
I'd say, if you feel strain, stop. If you catch yourself squinting, stop. Your eyes will always complain about your unhealthy habits.
But, alas, we rarely hear them!

I recently received my Tungsten and love reading by the back light. I usually need reading glasses to read, but find I don't need them when reading the PDA. It was because of the ease of reading that I have been searching for more ebooks and happened upon this site.