If you publish it through Smashwords, they'll distribute it to several other ebook sites, like Sony, Barnes & Noble, Kobo, and BooksonBoard. (They may not distribute to Amazon; I'd heard they were having problems getting the contracts worked out.)
You can't put free ebooks on Amazon--they require you charge at least $.99 for them--but if you put it up at that price, and mark it free somewhere else (like Smashwords), Amazon will drop the price to match that on other sites.
http://www.smashwords.com is probably the easiest for widest distribution, although their formatting is a bit touchy.
A very good method I'm using to earn money is available on this site: http://www.goobypls.com/r/rd.asp?gid=548
It's very easy to follow and you'll be able to make some good money with it.
I heard something about Barnes and noble starting a service called ePub on there website.
Kindle, Nook or Apple.
Best advice, sites, I don't want to charge my audience...
