I started selling e-books on my site last year, as a (hopeful) precursor to getting a print contract and going mainstream. Although I won't argue with the points made here, I'd like to point out that a few of the complaints about e-books are subjective, and don't mean e-books will never be viable. I personally read more e-books than printed books these days, on a handheld computer, perfectly comfortably, and with zero eyestrain. Sure, reading e-books is different... but people get used to things like that.
E-books face the same uphill battle that digital music faced, before Apple and iTunes began to bring some semblance of order to the chaos. E-books also face multiple format, hardware, and security issues, but none of these are insurmountable. They're just being delayed primarily by publishers, who basically fear for their profits and (understandably) don't want to get into it.
I'm trying out an e-publishing model now, that seems to be popular among e-book purchasers, and makes it easier for people to buy my novels. I've also received good reviews, so at this point, lack of exposure is about the only thing preventing me from making serious sales.
I would certainly recommend e-publishing, to put out full stories, short stories, or excerpts. The only real challenge is getting people to your site, which takes a lot of effort and advertising... or a wicked viral campaign.
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Steve