Now if the publishers would just "get it"
I've owned a 505 for a few months now, and it's probably my favorite device. I've always read more on a portable device since I can have it with me easier than paper books. I've never been a very fast reader, but I'm finding that my reading speed is increasing quite a bit since I started using the Sony. It's more comfortable to curl up with than a paperback since I don't have to hold it open, and I don't have to shift position for left/right side reading.
So far most publishers either don't do ebooks at all, or they price them the same as hardcovers (seriously, WTF?) - it's common to see $5.99 for softcover, $15 for hardcover, $18 for ebook. I don't even know what they're thinking there.
Or they have DRM. I've vowed not to buy ANY DRMd ebooks. Depending on your reading preferences, there may be tons of stuff out there that is free or at least doesn't have DRM. Baen Books _really_ gets it - they sell ebooks for a few bucks less than the paperback price, often just $4 or so, and they have a good selection of books from their popular science fiction authors available for free in their free library.
Baen books is currently the only publisher that's gotten ANY of my money, because they're the only company that is giving me what I want. And because I respect what they're doing, I'm also doing the right thing and keeping my paid-for copies to myself, but I *could* sell them if I wanted to, or I suppose give them away (and delete my copies). Same as with paper.
Also there's the mobileread.com community - if something is PD (especially if it's available in the Gutenberg library) some kind soul on mobileread has probably already done an excellent job of formatting it for your reader. I just read Orwell's 1984 a few weeks ago, and the Sony LRF copy on mobileread was very nicely done indeed.